Programming Basics (C++ and Blocks)

Note : If you are an absolute beginner to programming, it is a good idea to use the code+blocks programming option in Tinkercad, and copy over the generated C++ code to Arduino IDE.

Comments

• Comments are for you – the programmer or any other human who might read your code

• Comments are not run on the Arduino board

C++	Blocks

C++	Blocks
/* multi-line comment */   // single line comment	Open   Open

Statements

• Statements are compiled into an ‘executable’ of 1s and 0s, which are run on the Arduino.

• Statements end with a ;

Variables

• Variables are containers to store intermediate data

• In C language, a variable needs to have a type, which specifies the nature and the size of data it holds

• Some of the standard data types are

• int : 16-bit integers in the range -32,768 to 32,767

• unsigned int : 16-bit positive integers (incl 0), 0 to 65535

• char : 8-bit integers from -128 to 127. Characters such as ‘0’, ‘A’, ‘a’, etc. are represented using ASCII (48, 65, 97 respectively - read up more!). BYTE is the same as unsigned char

• float : for floating point numbers such as 2.25, -5.875 (32-bits)

• Types can also be user-defined (through classes)

• Variables can be declared with or without initialization

A variable appearing on the left-hand side of an assignment statement assigns a value to it.

A variable value is used when it appears in a comparison or on the right-hand side of an expression/assignment.

Selection

• A program that executes all the statements in a sequence is probably not very interesting.

• Sometimes, a part of a program must be executed based on a certain condition (selection).

• Given below is an example of an if-else statement. The {} is optional if there is only one line being executed conditionally for if or else.

To Do : Read up about switch-case

Iteration

• Sometimes, a part of a program must be executed repeatedly until a certain condition is satisfied (iteration / loop)

• Given below is an example for an while loop.

To Do : Read up about for loop, do-while loop

Functions

• A function is a segment of code which can be invoked from different parts of the program in a parameterized manner

• A function involves 3 aspects

• Declaration (typically done in header files with extension .h)

• Definition (typically done by the library vendor)

• Usage (usually, we need to do only this)

Note : Blocks do not allow you to declare or define functions explicitly. However, some built-in functions such as digitalWrite() can be called using appropriate blocks, as shown below.

Setup() and loop() functions

• Setup and loop are functions called automatically (unlike all other functions needs to be called explicitly)

• setup() is called once, when you release the reset button / plug in your Arduino / upload a new code onto the board

• loop() is called repeatedly; anything inside the loop() gets executed over and over as long as the system remains powered on

Note : When using blocks, any setup code required is automatically inserted into setup(). The main program logic which implemented using blocks goes into loop().

Good Coding Styles / Practices

Good code is code which is readable, comprehensible, and extensible. If you can't read/comprehend, you can't debug the code, you can't improve the code, you can't collaborate in a team. Hence the importance of following good coding styles/practices.

• Write detailed comments. This will be very useful later for you yourself or other people who read your code.

• Use descriptive variable names for variable etc. rather than short, generic names like i, j, k. This will help your code more readable and comprehensible.

• Indent your code properly. Indent with tabs, not with spaces. This also makes your code easier to read.

• Use constants/variables for values that appear at multiple places rather than hard-coding values.

Poor Coding Style

Good Coding Style