# Lovelace

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
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

# Course project 2019¶

NOTE! This is updated every now and then, so check back frequently.
The future technology megatrends IoT and AI are becoming massive. In this course, we aim to equip students with such basic skills and in the course project, we implement a real-world wearable computing AI application with SensorTag.
(Don't worry the term AI just yet, please read further.. basically you need to just implement a simple analysis for some sensor data)

# HIGH FIVE¶

Your task in the course project is to identify hand gestures (See gesture recognition) from the data produced by the MPU9250 sensor of the SensorTag. The first gesture you must recognize is the high five (as it is commonly known) and another gesture which you can freely select by yourself. When your program has recognized a gesture, it sends a broadcast message to the other devices in range. The other users are supposed to reply to your message by a hand gesture (..and the following message).

## Requirements¶

Your SensorTag application must be able to detect the high five and any other-hand gesture in a way that it can be demonstrated. How to detect the gesture is up to you.
Your application must have the following features:
1. Minimal user interface.
2. Use the MPU9250 sensor for gesture data collection. You can of course use other sensors.
3. The recognition algorithm must detect the high five-gesture (in a way its understood by common sense) and another gesture that you can define by youself.
• Gesture must include some movement and a hand posture.
• Static hand / posture is not a gesture.
4. Your application must inform the user about the recognized gesture in its display.
7. Your application implementation must be based on finite-state-machine.
You can also test, evaluate and use your application with battery, i.e. detached from the workstation. You can find the instructions here.

### Artificial intelligence?¶

Nowadays the vast majority of AI research and applications focuses on large-scale Big Data analytics and machine learning based on statistics. However, as these are not the topics of our course, we have a much simpler idea.
Your application needs to calculate some simple data features from collected sensor data and then classify the actions (i.e. gestures) based on comparison of the collected features and precalculated gesture features.
IMPORTANT! As statistics and AI are not in focus of this course, we will NOT grade the course project in this regard, i.e. the quality of your gesture recognition algorithm is not graded. However, you must be able to demonstrate a functional application in the grading session.
You can think of the gesture recognition in three phases:
1. Collect a dataset for initial analysis by performing a set of gestures (that you want to detect). With the MPU9250 sensor, you get three axis data of both acceleration and gyroscope that you can use to analyze hand movement and hand posture/pose. Note that the MPU9250 software library used in the course gives you angular velocity.
Now, the collected data set gives you information on what happens during the gestures with respect to these features.
2. The gesture recognition can be based, in general, to comparison of simple data features such as:
1. Tresholding: find out what are threshold for different modes
2. Data features: average, variance, standard deviation, ...
• Variance can be calculated for example with the algorithm here.
3. Building a model/profile of different modes. This approah could be much more difficult. Then, you can use correlation for mode detection.
4. ... you name it.
As a result, you get a set of features that describe the gestures through acceleration and hand posture, for example:
• What is the starting posture of your hand
• How to detect movement in the data?
• What is the ending posture of your hand
• How much error (dritfing, etc) you allow during the gesture?
• etc..
3. Next, you can perform the gesture recognition on-line on the SensorTag device by calculating the selected features from the data and by performing the classification through for example some comparison.

### Data set for testing¶

Course staff ahs collected initial data set for testing of the the high five hand gesture with the MPU9250 sensors.
Below, the data format in the example files is: [timestamp, acc_x, acc_y, acc_z, gyro_x, gyro_y, gyro_z].
1. Acceleration: In the figure below, you see the acceleration values (of one axis) during the gesture. X-axis shows the time. (IDLE just means the device was stationary.)
2. Gyroscope /angular velocity: In the figure below, you see the angular velocity during the gesture. X-axis shows the time. (IDLE just means the device was stationary.)
Test data as plain text:
high5-raw
Test data as C header file:

## Extra features¶

• 1 point features (Extra stuff in the UI)
• The program sends several and different types of messages.
• Produce some sound with buzzer.
• User feedback through messages and leds, etc.
• ...
• 2 point features (using additional SensorTag components)
• Read data from other sensors, show it on the display, etc.
• Pixel graphics in your application.
• Animated pixel graphics in your application.
• The buzzer plays "music/musical piece".
• Your application detects movement in on-line during the measurement. E.g. somehow informs the user about the phase of the gesture.
• Your data analysis performs some kind of evaluation of the performed gesture.
• ...
• 3 point features (significant own programs features)
• Your application reconizes more than two gestures.
• Teach the user to perform the gesture.
• ...
Every new feature is counted only once, i.e. additional sensors don't add up the score.
When evaluating the features for grading, the teacher's extensive experience in embedded programming and common sense is used.

It could be a good idea to start working on the project with Top-down design. This way you can partition a bigger problem into smaller problems that are easy to tackle in turn.
• A good design significantly reduces the amount of implementation work
• Do not leave the work for last minute, you will not succeed. Years of experience tells us that beginners can't finish the project in time, even when they have previous experience with embedded systems, in a week or two.
• Check the features and APIs that TI RTOS:n provides for SensorTag
• It might be beneficial to code algorithms and such first in PC, before moving the working code into the device.
• Implement debugging for your project, its signicficantly reduces the time used for bug hunting
IMPORTANT! If you get stuck, do not delay your work but visit the exercise sessions.

This chapter will be updated as the work progresses..
• You can find an example FSM for embedded application in the lecture material (Finnish). Please note that it does not work in your program exactly like it is.
• Split the program functionality into tasks, which all have proper functionality, e.g. sensor data collection, updating the display, wireless communication, etc.
• Implement On/Off button for the sensor data collection
• Code example of using the MPU9250 is here.
• Perhaps its a good idea to collect sensor data into an array.
• Please note the size of the array, i.e. how much memory it uses. Yoi have maximum 20kB, where everything in your program must fit.
• Figure out the sample rate for your recognition algorithm. This is your own software design decision.
• Fet timstamps for your data by using the function Clock_getTicks() from the Clock library.
• You could also clean-up / filter your sensor data with some common algorithm like moving average.
• Implement the initialization of some peripheral devices to the tasks, because you need to first start the BIOS, because the initialization needs that functionality.
• Of course, when using SensorTag with a battery, it may run out. Especially if you leave it running overnight. Just ask for new batteries during the exercise sessions.

This could a working order of how to implement your application
1. In device Collect your dataset for the recognition algorithm.
2. In workstation implement your recognition algorithm with C and using your data set.
3. In device test your algorithm on-line.
4. Implement the user interface and wireless messaging.
5. Extra features.

### Collecting test data¶

You could use a laptop to collect your own real-world data. Just implement a task for your SensorTag program that reads the sensor data, for example in an array, and outputs it to debug console in the end of the collection. You can then copy&paste the data to text editor and use Python (matplotlib) or gnuplot or M\$ Excel or to such application to visualize the data.
Note that when you start your program with the MPU9250 sensors, it performs internal calibration. So please put the device into solid flat surface in the beginning.
When collecting data, try to always perform the collection exatcly the same way. Otherwise your data may not actually be comparable with your previously collected data.

# Design documentation¶

As an obligatory part of the course project, you need to provide short (max one page) design documentation of your ideas. This is your private document that helps you to understand what exactly is needed to do in the course project.
Your design can be high level, no need to dig deep into the details. Here is a simple example of a design document.
Contents of the document:
1. Outline of what is shown in the device display and what UI components, will be used, e.g. buttons and leds.
2. Short description of the functionality of your program,
• Data structures, constants, global variables, ...
3. Describe how to collect the sensor data
• Data size, periods, etc, ..
4. High level finite state machine that controls the program execution
• Just a picture needed
5. Possibly the additional extra features
6. Estimation of how much RAM (approximately) your application needs
7. Your own estimation of what could be difficult in the project

## Returning design documentation¶

The deadline for the design documentation is 6th October. If you miss the deadline without justified cause, your course project score is reduced three points (see below). It is enough that either student of the group returns the document, but it must have the names of all group members.

Upload your design document into this exercise. Use a well-known fileformat, i.e. JPG/PNG/PDF/Word document.
Note! Do not send large files (i.e. size of several megabytes), but try to reduce the image size.
Palautettavan tiedoston maksimikoko on 2,5 MB!
Warning: You have not logged in. You cannot answer.
note! You can of course start working on your project, before returning the document.
Note! We may use the documentation as a source material for academic research. If you want to prevent using your documentation, mark this into the document.

The course project deadline is Sunday 17th November 2019 at 23:59.
Upload your source code files to the box below before the deadline. This source code is the graded code. It is ok for one student per group to upload the code. (In any case, you must do the upload, as it is required by Finnish law to store your course work for at least six months.)
Upload the code by the following instructions:
• Only your own code main.c and additional files mylib.c ja mylib.h.
• Do not return RTOS code, or the code in sensors and wireless directories.
• If you upload several files, pack them with zip first.
• Never just pack the whole project directory, as it contains large unnecessary debug files etc.

## Course project code¶

Please do not zip and upload the whole project directory, as there are lots of unnecessary extra stuff including large debug files, etc!
Warning: You have not logged in. You cannot answer.

• All members of group MUST be present.
• Missing students don't get grades until they demonstrate their contribution to the project.
• You need to present your code to the teacher, who will ask questions ab out your solution.
• In the end, your score is presented.
The maximum score of your project is max 30 points that is 50% of the overall course grade. The other 50% comes from the C programming exercise. You must have points from both exercises and projects to pass the course.
Scoring:
1. Design document: 0 / -3p
2. Program follows requirements: 10p
• Bugs or missing feature: -2p / each
• If you explain how to fix the bug: -1p
3. Code quality: 0-5p
• The program implementation follows a finite state machine: 3p
• the structure of code is modular and uses functions: 1p
• Variable and function names are reasonable, code has comments and proper indentation is used: 1p
• Each feature 1-3p

# FAQ¶

1. Can I do the project alone?
• Yes, however your workload is then more than with a peer.
2. Can we have a group of three students?
• Yes, but you have to implement additional extra features worth 5 points into your project.
3. Can I discuss my project with others?
• Yes of course, but you still have to implement your own code. If you copy the code, you may be guilty of plagiarism, which may lead you to very serious trouble. Therefore, please write into the code comments the names of students you co-operated with.
4. Can I return the project late?
• It's not worth it, we will reduce your total grade by -1. This is the actual grade, not points!
• If you have a justified cause to return the project late, please inform the course teacher beforehand. Typically justified causes are well-known early.
5. Can I use code that I found from the Internet?
• Sure, but you must inform the source (e.g. www page) in your code comments. Othwerise you may be guilty of plagiarism.
6. .. plagiarism?
• The university has strict rules regarding plagiarism. We follow those rules, where students can find themselves in serious trouble, if found guilty of plagiarism.
?
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).