Termbank
  1. A
    1. Abstraction
    2. Alias
    3. Argument
    4. Array
  2. B
    1. Binary code file
    2. Binary number
    3. Bit
    4. Bitwise negation
    5. Bitwise operation
    6. Byte
  3. C
    1. C library
    2. C-function
    3. C-variable
    4. Character
    5. Code block
    6. Comment
    7. Compiler
    8. Complement
    9. Conditional statement
    10. Conditional structure
    11. Control structure
  4. D
    1. Data structure
    2. Duck typing
  5. E
    1. Error message
    2. Exception
  6. F
    1. Flag
    2. Float
  7. H
    1. Header file
    2. Headers
    3. Hexadecimal
  8. I
    1. Immutable
    2. Initialization
    3. Instruction
    4. Integer
    5. Interpreter
    6. Introduction
    7. Iteroitava
  9. K
    1. Keyword
  10. L
    1. Library
    2. Logical operation
  11. M
    1. Machine language
    2. Macro
    3. Main function
    4. Memory
    5. Method
  12. O
    1. Object
    2. Optimization
  13. P
    1. Parameter
    2. Placeholder
    3. Pointer
    4. Precompiler
    5. Precompiler directive
    6. Prototype
    7. Python console
    8. Python format
    9. Python function
    10. Python import
    11. Python list
    12. Python main program
    13. Python variable
    14. Python-for
    15. Pääfunktio
    16. printf
  14. R
    1. Resource
    2. Return value
  15. S
    1. Statement
    2. Static typing
    3. String
    4. Syntax
  16. T
    1. Terminal
    2. Type
    3. Typecast
  17. U
    1. Unsigned
  18. V
    1. Value
  19. W
    1. Warning
    2. while
Completed: / exercises

FAQ: Answers to Questions and Feedback

On this page, we answer the questions and comments raised in the feedback regarding the C language section of the course, divided by lecture chapters.

About Completing the Course

Q: I couldn’t finish the course last year. Do I need to start from scratch?
A: No. The course completions for JTKJ and/or TKJ courses are valid for one year, so you only need to complete the missing parts of the course. However, you need to complete the entire block: C programming and the course project.
Q: What exactly does the exercise deadline mean?
A: Points towards the final grade are awarded for exercises from lecture chapters 1-12 that are completed by the deadline. These exercises can be found on the Exercise subpages of the course materials. Introductory or ungraded lecture tasks within the materials do not contribute to the grade.
Q: Will I be penalized in the exercises if I attempt the same task multiple times?
A: No, you won’t. You can attempt each task as many times as needed. You get points when the checker approves your answer. However, we do not recommend using Lovelace as a C language error checker... it’s better to ask the assistants. There is only one exception. There are some questions that limit the number of answer. If you exceed the limit, your exercise wont be evaluated.
Q: The schedule for the lab session week doesn’t work for me at all!
A: Discuss this with the course staff. Without attending the lab, you won’t be able to get the development board.
Q: Can I complete the project with Arduino or other platform?
A: Generally, no. However, if you have built an embedded system as a hobby or something similar using Arduino or a similar platform, you can propose it, and we will see if it meets the course project requirements.
Q: As a minor subject student (or equivalent), I am simultaneously taking the Elementary Programming course and the JTKJ course. I’m struggling with the JTKJ tasks because they require knowledge that hasn’t yet been covered in the Elementary Programming course.
A: The Elementary Programming course is a prerequisite for JTKJ. The courses are not designed to be taken at the same time, and the course materials are not synchronized. The course instructors have no control over this, so please give feedback to those responsible for your studies.
Q: I do not live in Oulu. Can I take the course remotely?
A: The course is part of an in-person degree program, and attendance may be required for mandatory events such as laboratory exercises or final meetings. Depending on the situation, the course staff may offer alternatives, but these are provided on a case-by-case basis and are not guaranteed (exceptions are generally denied). In any case, the student must arrange to acquire the development platform themselves. Under no circumstances will we post any of the equipment.

About Lovelace

Q: The checker program keeps crashing.
A: We are very interested in hearing about this. Could you please show us during the lab or send a message explaining exactly how the crash occurs? Please include the URL of your submission.
When you receive a JSONDecodeError in Lovelace, it usually means that you have memory problems in your code (basically, you are trying to use memory positions that you are not supposed to use, e.g., overflow). In that case, the checker will kill the process. Check your loops carefully and make sure you are not trying to read/modify array positions outside their limits.
There is absolutely nothing we can do if the checker crashes due to your submission violating memory limits. It is impossible to retrieve anything from the checker because the OS kills the entire process stack immediately when you try to access memory outside of your reserved area. If you get a "checker crashed" report, your program likely has this issue.
Q: I submitted feedback, but I haven’t heard anything since. What’s wrong?
A: Feedback is shown to us anonymously, so we don’t know who to contact. We don’t publish solutions to the exercises, at least not until after the deadline.

C Language Exercises

Codeblocks

Q: When I try to compile/run my code in Codeblocks, I get this message: ''undefined reference to 'WinMain'
A:
Check that the main function is implemented.
Check that the main function is only in one file.
Ensure that you have created a "Console application" project, not a "Windows GUI".
Restart Codeblocks.

3. Bits and Number Systems

Q: I get frustrated with number system conversions and bit operations... and hey!, calculators exist!
A: These are such fundamental skills for a computer/electrical engineer that you should really be able to do them in your head.
Q: How can I represent a binary number in C? I saw the prefix 0b used online.
A: The prefix 0b is not standard C but an extension in some compilers. In the gcc compiler used in this course, it is working.
Binary numbers can easily be represented as hexadecimal; see the lecture materials.
Q: In hexadecimal, negative numbers usually have a minus (-) sign instead of the higher bits like 8(0b1000) and above.
A: That's true, you can use the minus sign with hexadecimal numbers as well. However, the computer internally handles these negative hexadecimal numbers as 2’s complement values, meaning the compiler does the conversion automatically.
Note that the assignment int8_t neg = -0x81 (which seems like "two minus signs") doesn’t fit within the value range and requires a 9th sign bit, which means the 8th bit is interpreted as part of the value.
In the course, we use the 2’s complement representation. For instance, when reading the register of a peripheral device, the only way to pass both positive and negative numbers is through 2’s complement.

5. Bitwise Operations in C

Q: If we're being precise, doesn’t the operations order table at the end miss the left-to-right post-increment and post-decrement operators (++ and --)? The table seems to only show the right-to-left 'first assign, then reference' versions of the ++ and -- operators. Example:
uint8_t n = 4;
printf("%d\n", n++); // <- missing, returns 4
printf("%d\n", ++n); // returns 6
printf("%d\n", --n); // returns 5

// for some reason, ++i and --i work the same as i++ and i-- in loops?!?
for (uint8_t i; i < 10; i++) {} 
for (uint8_t i; i < 10; ++i) {}
A: Good question, there are a few things to consider here.
1) The table is meant to describe the order of precedence by rows, with higher precedence at the top. The direction of evaluation (whether left-to-right or right-to-left) depends on the row.
Evaluation direction means that if you have multiple operators of the same precedence in one statement, in what order are they evaluated, from right to left or left to right? For operator Q: (a Q b) Q c or a Q (b Q c)? On this course, you won’t need to worry about this if you use parentheses.
2) Additionally, when using these unary operators as function parameters, be careful, as the evaluation order (binding order) is compiler-dependent. This is discussed in the textbook (Kernighan & Ritchie, section 2.12).
// Here, we don’t know which operation happens first, ++ or pow()
printf("%d %d", ++n, pow(2,n));
// A clearer way to do this would be (for example)
++n;
printf("%d %d", n, pow(2,n));
3) Finally, in a for-loop, the assignment operation always comes last. So it doesn’t matter whether you use ++ before or after, as it will always be executed at the end of the iteration.

7. Control Structures in C

Q: I can't print 64-bit numbers with printf. (I found a weird %PRI64d format specifier on Google that seems to work.)
A: Printing large numbers may require the use of the format specifier %lld (long long int), depending on the architecture and compiler, as %ld might not be enough. In some compilers, you might need to use %i64d as the format specifier.

SensorTag Programming

Q: How do I print sensor data to the console window?
A: Strings are printed to the console’s debug window using the System_printf function, which is covered in lecture material 8. Input and Output in C (the "thousand-dollar tips").
However... due to the way RTOS is implemented, the function should not be used like the standard library's print function, meaning you don't pass numerical values in the arguments to be printed in the string. You should proceed as follows:
1. Use the sprintf function to first create the desired string. Floats, integers, characters, etc., are printed into this string.
2. Pass this string as an argument to System_printf.
3. Finally, don’t forget to call System_flush, which actually prints the string to the console window.
Q: Why doesn't System_printf print anything?
A: The System_printf function only puts the message into the debugger’s buffer, and it is only sent to the waiting console on the other end of the USB cable when the entire buffer is flushed at once using the System_flush function.
In your program, decide whether you want to print a line at a time immediately to the console (by calling flush after each print), or if you prefer to collect the results in the buffer and flush multiple messages at once. The latter approach is faster for program execution since you aren't constantly sending messages between the device, debugger, and console.

SensorTag Device

Q: Something strange is happening, but I can't figure out where in the code it's coming from...
A: There are at least three ways to troubleshoot this:
1. Use debug print statements (like System_printf) to trace how the program execution progresses.
2. The debugger can be used to control the program execution literally one line at a time and inspect, for example, the variable values, allowing you to try to find the line causing the runtime error. However, sometimes the line where execution stops isn’t faulty, and in larger programs, the debug prints from point 1 can be a better way to trace the issue. Conversely, the debugger works better in cases where slow debug prints from point 1 interfere with the program’s operation.
3. You can always ask the teaching assistant in the chat or during the exercises.
A good solution for troubleshooting code issues independently is to use both debug prints and the debugger simultaneously!
Q: Why does SensorTag freeze immediately after startup or during execution?
A: There could be several reasons:
1. The device runs out of memory. There are a couple of things you should check here.
2. A handler that takes too long to execute can cause the device to hang, as the rest of the functionality (including RTOS) cannot proceed. Move the functionality out of the handler to the task code and control execution using a state machine. Often (always), the best practice for a handler is to simply set a state change and respond to it in the tasks.
3. A forgotten Task_sleep causes the task to run indefinitely, or there is an unnecessary long-running process in commtask (the task used for wireless communication).
4. Components/peripherals are being used outside the task where they were initialized. A common example is trying to print to or clear the display with Display_clear from multiple tasks. Fix this by implementing a state machine in displayTask.
Q: Why are only one of the tasks being executed?
A: Most likely, the task that is being executed doesn’t have a Task_sleep, which prevents other tasks from getting execution time. Remember that commtask (the task used for wireless communication) should not have a Task_sleep call!
Q: Why doesn’t the power button start SensorTag when it’s connected to the computer?
A: When the debugger is connected to the SensorTag, the device emulates standby mode. For reasons related to the debugger, the device can’t be awakened when being debugged, but you can test its functionality simply by disconnecting the debugger while the device is running. So, the power button should work when the SensorTag is connected to the computer via USB without interacting with the development environment. Also, due to the emulation, it’s recommended to use the SensorTag with a battery without the Debugger Devpack board.

Sensors

Q: I don’t know where to start with using sensors!
A: The use of the TMP007 temperature sensor is described in the lecture material as an example... copy & paste will get you a long way. There is an example of using the MPU9250 sensor in the project, which you can find in the students’ file sharing.
Q: I’m trying to add sensors to my program, but the compiler can’t find their library functions..
A: For sensors and other peripherals, you need to include the header file name.h for each sensor you are using. So, check what is in the sensors folder of the project template.
Remember to implement the functionality required by the name_get_data function that interprets the registers at the end of the corresponding sensor library code file.
Q: Sensor initialization (in x_setup function) fails!
A: There could be many reasons, but most often it’s because you are trying to open both I2C sensor buses at the same time. The i2c connection must always be closed before opening a new one.
Q: How can I visualize sensor data?
A: Some IDEs used for SensorTag programming even have a Graph feature, which you can use to create plots while debugging.
In the lecture material, the project chapter also gives tips for visualizing sensor data outside the development environment. You can use programs like M$ Excel, gnuplot, Python libraries, Matlab, etc.
It’s recommended to collect the sensor data in csv format, which most programs can read directly.

Graphics and Sound

Q: How do I get sound from the device?
A: SensorTag has a simple component that produces beeping sounds, called a buzzer. An example code file can be found in the students’ Github. The buzzer is connected to I/O pins, so you need the same pin configurations and setups as for a button, for example. The pin configuration can be found in the CC2650STK.c file between other familiar-looking lines. After calling buzzerOpen, you’ll naturally need to wait, for example, with Task_sleep, before calling buzzerClose to let the sound play.
There are plenty of examples online for playing songs with an embedded systems "ghettoblaster".
There may be a little tweaking required depending on the development environment for using the buzzer library from the students’ repository. If the compiler complains that it can’t find the driverLib/timer.h header file, try changing the folder path to use a lowercase or uppercase "L".
Q: How can I draw images on the screen using GrImageDraw?
A: An image is represented in bitmap format with ones and zeros, where one means the corresponding pixel is on. The graphics library and the GrImageDraw function will draw the image “correctly” — that is, the first row of a height * width image is determined by the first width bits from left to right.
The lecture material includes instructions for drawing 8x8 pixel images, and there is an example of drawing larger images on the screen in the students' file sharing.
You can draw images manually, pixel by pixel, using something like Paint, and then convert the image to hexadecimal by calculating it roughly yourself, or you could create your own image editor that converts the final image to hexadecimal. Ok, there are also bitmap image editors available online...

State Machine

Q: I copied the state machine example from the lecture material, but now I’m getting an expected an identifier or some similar error.
A: The material notes that the example doesn’t work as-is because of the IDLE state, as this constant is already used by RTOS. Consider renaming the states.
Q: How can I track the state machine’s behavior in multiple tasks?
A: By using debug print statements... so log the state changes of the state machine to the console window.

Development Environment and Console

Q: What is a debugger?
A: In embedded systems, a debugger is usually a separate physical device and associated software that allows you to control the behavior of the microcontroller and the execution of the program on it. A debugger is a very handy tool in embedded software development and is included with all modern devices and their development environments. The SensorTag debugger is the separate circuit board between the display and the device, where the green LED is always on.
Using the debugger involves setting up breakpoints in the code. You can have multiple breakpoints in the program at the same time. A breakpoint marks positions in the code (e.g., a circle or some symbol at the line of code in the editor) where you want the program execution to stop “live.” When the program stops, the debugger has access to the state of the device, memory, (sometimes even peripherals), and so on.
In the debugger software’s panel, there are various functions for program execution, such as running the program one line at a time (e.g., ‘‘step over’’) or running the program until the next breakpoint (‘‘run’’).

Conclusion

The person who asks questions does not get lost.
This course only gives a very faint glimpse of C and its usage. Just enough to learn how to use it as a tool for programming embedded systems.
?
Abstraction is a process through which raw machine language instructions are "hidden" underneath the statements of a higher level programming language. Abstraction level determines how extensive the hiding is - the higher the abstraction level, the more difficult it is to exactly say how a complex statement will be turned into machine language instructions. For instance, the abstraction level of Python is much higher than that of C (in fact, Python has been made with C).
Alias is a directive for the precompiler that substitus a string with another string whenever encountered. In it's basic form it's comparable to the replace operation in a text editor. Aliases are define with the #define directeve, e.g. #define PI 3.1416
Argument is the name for values that are given to functions when they are called. Arguments are stored into parameters when inside the function, although in C both sides are often called just arguments. For example in printf("%c", character); there are two arguments: "%c" format template and the contents of the character variable.
Array is a common structure in programming languages that contains multiple values of (usually) the same type. Arrays in C are static - their size must be defined when they are introduced and it cannot change. C arrays can only contain values of one type (also defined when introduced).
Binary code file is a file that contains machine language instructions in binary format. They are meant to be read only by machines. Typically if you attempt to open a binary file in a text editor, you'll see just a mess of random characters as the editor is attempting to decode the bits into characters. Most editors will also warn that the file is binary.
Binary number is a number made of bits, i.e. digits 0 and 1. This makes it a base 2 number system.
A bit is the smallest unit of information. It can have exactly two values: 0 and 1. Inside the computer everything happens with bits. Typically the memory contains bitstrings that are made of multiple bits.
Bitwise negation is an operation where each bit of a binary number is negated so that zeros become ones and vice versa. The operator is ~.
Bitwise operations are a class of operations with the common feature that they manipulate individual bits. For example bitwise negation reverses each bit. Some operations take place between two binary values so that bits in the same position affect each other. These operations include and (&), or (|) and xor (^). There's also shift operations (<< and >>) where the bits of one binary number are shifted to the left or right N steps.
Byte is the size of one memory slot - typically 8 bits. It is the smallest unit of information that can be addressed from the computer's memory. The sizes of variable types are defined as bytes.
External code in C is placed in libraries from which they can be taken to use with the #include directive. C has its own standard libraries, and other libraries can also be included. However any non-standard libraries must be declared to the compiler. Typically a library is made of its source code file (.c) and header file (.h) which includes function prototypes etc.
Functions in C are more static than their Python counterparts. A function in C can only have ne return value and its type must be predefined. Likewise the types of all parameers must be defined. When a function is called, the values of arguments are copied into memory reserved for the function parameters. Therefore functions always handle values that are separate from the values handled by the coe that called them.
C variables are statically typed, which means their type is defined as the variable is introduced. In addition, C variables are tied to their memory area. The type of a variable cannot be changed.
Character is a single character, referred in C as char. It can be interpreted as an ASCII character but can also be used as an integer as it is the smallest integer that can be stored in memory. It's exactly 1 byte. A character is marked with single quotes, e.g. 'c'.
Code block is a group of code lines that are in the same context. For instance, in a conditional structure each condtion contains its own code block. Likewise the contents of a function are in their own code block. Code blocks can contain other code blocks. Python uses indentation to separate code blocks from each other. C uses curly braces to mark the beginning and end of a code block.
Comments are text in code files that are not part of the program. Each language has its own way of marking comments. Python uses the # character, C the more standard //. In C it's also possible to mark multiple lines as comments by placing them between /* and */.
A compiler is a program that transforms C source code into a binary file containing machine language instructions that can be executed by the computer's processor. The compiler also examines the source code and informs the user about any errors or potential issues in the code (warnings). The compiler's behavior can be altered with numerous flags.
Complement is a way to represent negative numbers, used typically in computers. The sign of a number is changed by flipping all its bits. In two's complement which is used in this course, 1 is added to the result after flipping.
Conditional statement is (usually) a line of code that defined a single condition, followed by a code block delimited by curly braces that is entered if the condition evaluates as true. Conditional statements are if statements that can also be present with the else keyword as else if. A set of conditional statements linked together by else keywords are called conditional structures.
Conditional structure is a control structure consisting of one or more conditional statements. Most contrl structures contain at least two branches: if and else. Between these two there can also be any number of else if statements. It is however also possible to have just a single if statement. Each branch in a conditional structure cotains executable code enclosed within a block. Only one branch of the structure is ever entered - with overlapping conditions the first one that matches is selected.
Control structures are code structures that somehow alter the program's control flow. Conditional structures and loops belong to this category. Exception handling can also be considered as a form of control structure.
Data structure is a comman name for collection that contain multiple values. In Python these include lists, tuples and dictionaries. In C the most common data structures are arrays and structs.
Python's way of treating variable values is called dynamic typing aka duck typing. The latter comes from the saying "if it swims like a duck, walks like a duck and quacks like a duck, it is a duck". In other words, the validity of a value is determined by its properties in a case-by-case fashion rather than its type.
An error message is given by the computer when something goes wrong while running or compiling a program. Typically it contains information about the problem that was encountered and its location in the source code.
An exception is what happens when a program encounters an error. Exceptions have type (e.g. TypeError) that can be used in exception handling within the program, and also as information when debugging. Typically exceptions also include textual description of the problem.
Flags are used when executing programs from the command line interface. Flags are options that define how the program behaves. Usually a flag is a single character prefixed with a single dash (e.g. -o) or a word (or multiple words connected with dashes) prefixed with two dashes (e.g. --system. Some flags are Boolean flags which means they are either on (if present) or off (if not present). Other flags take a parameter which is typically put after the flag separated either by a space or = character (e.g. -o hemulen.exe.
Floating point numbers are an approximation of decimal numbers that are used by computers. Due to their archicture computers aren't able to process real decimal numbers, so they use floats instead. Sometimes the imprecision of floats can cause rounding errors - this is good to keep in mind. In C there are two kinds of floating point numbers: float and double, where the latter has twice the number of bits.
Header files use the .h extension, and they contain the headers (function prototypes, type definitions etc.) for a .c file with the same name.
Headers in C are used to indicate what is in the code file. This includes things like function prototypes. Other typical content for headers are definition of types (structs etc.) and constants. Headers can be at the beginning of the code file, but more often - especially for libraries - they are in placed in a separate header (.h) file.
Hexadecimal numbers are base 16 numbers that are used particularly to represent memory addresses and the binary contents of memory. A hexadecimal number is typically prefixed with 0x. They use the letters A-F to represent digits 10 to 15. Hexadecimals are used because each digit represents exactly 4 bits which makes transformation to binary and back easy.
In Python objects were categorized into mutable and immutable values. An immutable value cannot have its contents changed - any operations that seemingly alter the object actually create an altered copy in a new memory location. For instance strings are immutable in Python. In C this categorization is not needed because the relationship of variables and memory is tighter - the same variable addresses the same area of memory for the duration of its existence.
When a variable is given its initial value in code, the process is called initialization. A typical example is the initialization of a number to zero. Initialization can be done alongside with introduction: int counter = 0; or separately. If a variable has not been initialized, its content is whatever was left there by the previous owner of the memory area.
Instruction set defines what instructions the processor is capable of. These instructions form the machine language of the processor architecture.
Integers themselves are probably familiar at this point. However in C there's many kinds of integers. Integer types are distinguished by their size in bits and whether they are signed or not. As a given number of bits can represent up to (2 ^ n) different integers, the maximum value for a signed integer is (2 * (n - 1))
Python interpreter is a program that transforms Python code into machine language instructions at runtime.
The moment a variable's existence is announed for the first is called introduction. When introduced, a variable's type and name must be defined, e.g. int number;. When a variable is introduced, memory is reserved for it even though nothing is written there yet - whatever was in the memory previously is still there. For this reason it's often a good idea to initialize variables when introducing them.
Iteroitava objekti on sellainen, jonka voi antaa silmukalle läpikäytäväksi (Pythonissa for-silmukalle). Tähän joukkoon kuuluvat yleisimpinä listat, merkkijonot ja generaattorit. C:ssä ei ole silmukkaa, joka vastaisi Pythonin for-silmukan toimintaa, joten taulukoiden yms. läpikäynti tehdään indeksiä kasvattavilla silmukoilla.
Keywords are words in programming languages that have been reserved. Good text editors generally use a different formatting for keywords (e.g. bold). Usually keywords are protected and their names cannot be used for variables. Typical keywords include if and else that are used in control structures. In a way keywords are part of the programming language's grammar.
A library is typically a toolbox of functions around a single purpose. Libraries are taken to use with the include directive. If a library is not part of the C standard library, its use must also be told to the compiler.
Logical operation refers to Boole's algebra, dealing with truth values. Typical logical operations are not, and, or which are often used in conditional statements. C also uses bitwise logical operations that work in the same way but affect each bit separately.
Machine language is made of instructions understood by the processor. Machine language is often called Assembly and it is the lowest level where it's reasonable for humans to give instructions to computers. Machine language is used at the latter part of this course - students taking the introduction part do not need to learn it.
Macro is an alias that defines a certain keyword to be replaced by a piece of code. When used well, macros can create more readable code. However, often the opposite is true. Using macros is not recommended in this course, you should just be able to recognize one when you see it.
In C the main function is the starting point when the program is run. The command line arguments of the program are passed on to the main function (although they do not have to be received), and its return value type is int. At its shortest a main function can defined as int main().
When programs are run, all their data is stored in the computer's memory. The memory consists of memory slots with an address and contents. All slots are of equal size - if an instance of data is larger, a continuous area of multiple memory slots is reserved.
Method is a function that belongs to an object, often used by the object to manipulate itself. When calling a method, the object is put before the method: values.sort().
Object is common terminology in Python. Everything in Python is treated as objects - this means that everything can be referenced by a variable (e.g. you can use a variable to refer to a function). Objects are typically used in object-oriented languages. C is not one.
Optimization means improving the performance of code, typically by reducing the time it takes to run the code or its memory usage. The most important thing to understand about opimization is that it should not be done unless it's needed. Optimization should only be considered once the code is running too slowly or doesn't fit into memory. Optimization should also not be done blindly. It's important to profile the code and only optimize the parts that are most wasteful.
A parameter is a variable defined alongside with a function. Parameters receive the values of the function's arguments when it's called. This differentation between parameters and arguments is not always used, sometimes both ends of the value transfer are called arguments.
Placeholders are used in string formatting to mark a place where a value from e.g. a variable will be placed. In Python we used curly braces to mark formatting placeholders. In C the % character is used which is followed by definitions, where the type of the value is mandatory. For instance "%c" can only receive a char type variable.
Pointers in C are special variables. A pointer contains a memory address of the memory location where the actual data value is located. In a sense they work like Python variables. A variable can be defined as a pointer by postfixing its type with * when it's being introduced, e.g. int* value_ptr; creates a pointer to an integer. The contents of the memory address can be fetched by prefixing the variable name with * (e.g. *value_ptr. On the other hand, the address of a memory adress can be fetched by prefixing a variable name with &, (e.g. &value.
The C precompiler is an apparatus that goes through all the precompiler directives in the code before the program is actually compiled. These directives include statements which add the source code of the included libraries into the program, and define directives that can define constant values (aliases) and macros.
Directives are instructions that are addressed at the precompiler. They are executed and removed from the code before the actual compilation. Directives start with the # character. The most common one is include which takes a library into use. Another common one is define, which is used e.g. to create constant values.
Prototype defines a function's signature - the type of its return value, its name and all the arguments. A prototype is separate from the actual function definition. It's just a promise that the function that matches the prototype will be found in the code file. Prototypes are introduced at the beginning of the file or in a separate header file. In common cases the prototype definition is the same as the line that actually starts the function introduction.
Interactive interpreter or Python console is a program where users can write Python code lines. It's called interactive because each code line is executed after its been fully written, and the interpreter shows the return value (if any).
The format method of string in Python is a powerful way to include variable values into printable text. The string can use placeholders to indicate where the format method's arguments are placed.
Python functions can have optional parameters that have a given default value. In Python the values of arguments in a function call are transferred to function parameters through reference, which means that the values are the same even though they may have different names. Python functions can have multiple return values.
In Python the import statement is used for bringing in modules/libraries - either built-in ones, thrid party modules or other parts of the same application. In Python the names from the imported module's namespace are accessible through the module name (e.g. math.sin). In C libraries are taken to use with include, and unlike Python import it brings the library's namespace into the program's global namespace.
Python lists were discovered to be extremely effective tools in Elementary Programming. A Python list is an ordered collection of values. Its size is dynamic (i.e. can be changed during execution) and it can include any values - even mixed types. Lists can also include other lists etc.
In Python main program is the part of code that is executed when the program is started. Usually the main program is at the end of the code file and most of the time under if __name__ == "__main__": if statement. In C there is no main program as such, code execution starts with the main function instead.
In Python a variable is a reference to a value, a connection between the variable's name in code and the actual data in memory. In Python variables have no type but their values do. The validity of a value is tested case by case when code is executed. In these ways they are different from C variables, and in truth Python variables are closer to C pointers.
Pythonin for-silmukka vastaa toiminnaltaan useimmissa kielissä olevaa foreach-silmukkaa. Se käy läpi sekvenssin -esim. listan - jäsen kerrallaan, ottaen kulloinkin käsittelyssä olevan jäsenen talteen silmukkamuuttujaan. Silmukka loppuu, kun iteroitava sekvenssi päättyy.
Pääfunktio on C:ssä ohjelman aloituspiste ja se korvaa Pythonista tutun pääohjelman. Oletuksena pääfunktion nimi on main ja se määritellään yksinkertaisimmillaan int main().
Resource referes to the processing power, memory, peripheral devices etc. that are availlable in the device. It includes all the limitations within which programs can be executed and therefore defines what is possible with program code. On a desktop PC resources are - for a programmer student - almost limitless, but on embedded devices resources are much more scarce.
Return value is what a function returns when its execution ends. In C functions can only have one return value, while in Python there can be multiple. When reading code, return value can be understood as something that replaces the function call after the function has been executed.
A statement is a generic name for a single executable set of instructions - usually one line of code.
C uses static typing This means that the type of variables is defined as they are created, and values of different types cannot be assigned to them. The validity of a value is determined by its type (usually done by the compiler). Python on the other hand uses dynamic typing aka.duck typing.
In Python all text is handled as strings and it has no type for single characters. However in C there are no strings at all - there's only character arrays. A character array can be defined like a string however, e.g. char animal[7] = "donkey"; where the number is the size of the array + 1. The +1 is neede because the string must have space for the null terminator '\0' which is automatically added to the end of the "string".
Syntax is the grammar of a programming language. If a text file does not follow the syntax of code, it cannot be executed as code, or in the case of C, it cannot be compiled.
Terminal, command line interface, command line prompt etc. are different names to the text-based interface of the operating system. In Windows you can start the command line prompt by typing md to the Run... window (Win+R). Command line is used to give text-based commands to the operating system.
The data in a computer's memory is just bits, but variables have type. Type defines how the bits in memory should be interpreted. It also defines how many bits are required to store a value of the type. Types are for instance int, float and char.
Typecast is an operation where a variable is transformed to another type. In the elementary course this was primarily done with int and float functions. In C typecast is marked a bit differently: floating = (float) integer}. It's also noteworthy that the result must be stored in a variable that is the proper type. it is not possible to change the type of an existing variable.
Unsigned integer is a an integer type where all values are interpreted as positive. Since sign bit is not needed, unsigned integers can represent twice as large numbers as signed integers of the same size. An integer can be introduced as unsigned by using the unsigend keyword, e.g. unsigned int counter;.
In the elementary programming course we used the term value to refer to all kinds of values handled by programs be it variables, statement results or anything. In short, a value is data in the computer's memory that can be referenced by variables. In C the relationship between a variable and its value is tighter as variables are strictly tied to the memory area where its value is stored.
A warning is a notification that while executing or - in this course particularly - compiling it, something suspicious was encountered. The program may still work, but parts of it may exhibit incorrect behavior. In general all warnings should be fixed to make the program stable.
One way to print stuff in C is the printf function, which closely resembles Python's print function. It is given a printable string along with values that will be formatted into the string if placeholders are used. Unlike Python, C's printf doesn't automatically add a newline at the end. Therefore adding \n at the end is usually needed.
Out of loops, while is based on repetition through checking a condition - the code block inside the loop is repeated until the loop's condition is false. The condition is defined similarly to conditional statements, e.g. while (sum < 21).