Arduino variables and constants

Before we begin to explain variable types, we need to identify a very important topic, called variable ranges.

What is a variable range?

The variable in the C language used by Arduino has a property called scope. s cope is an area of the program where three places can declare variables. They are:

• Inside a function or block of code, it is called a local variable.
• In the definition of a function argument, it is called a formal argument.
• Outside of all functions, it is called a global variable.

The local variable

The variable declared in a function or block of code is a local variable. /b10> They can only be used by statements in the function or block of code. /b11> Local variables cannot run outside of themselves. The following is an example of using a local variable:

Void setup () {

}

Void loop () {
   int x , y ;
   int z ; Local variable declaration
   x = 0;
   y = 0; actual initialization
   z = 10;
}

Global variable

Global variables are defined outside of all functions and are usually at the top of the program. /b10> Global variables maintain their value throughout the life of the program.

Global variables can be accessed by any function. /b10> That is, a global variable can be used after being declared throughout the program.

The following example uses global and local variables:

Int T , S ;
float c = 0 ; Global variable declaration

Void setup () {

}

Void loop () {
   int x , y ;
   int z ; Local variable declaration
   x = 0;
   y = 0; actual initialization
   z = 10;
}