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Constant Variable in C++ Programming

C++ Basic Concepts

In this lesson, we will look at what is constant variable and how to declare one with the help of some example. We will also play a quiz at the end.

What is Constant Variable

A Constant variable in C++ is a variable whose value does not change during the execution of the program. Once a value is assigned, in a constant variable, it remains fixed throughout the program. A Constant variable is declared by keyword const.


Syntax of Declaring Constant Variable in C++

const datatype variable_name;

Here const is used for declaring Constant, datatype is the name of data type such as int, float, double or char and variable_name is the name of variable (you can use any name of your choice for example: a, b, c, alpha, etc.) and ; is used for line terminator (end of line).

Now let's see the example for more understanding.


Declare constant variables of each datatype.

const int a = 23;  		    // a becomes integer constant variable
const float b = 56.36;  	// b becomes float constant variable
const double c = 75.3215;  	// c becomes double constant variable
const char d = 'k';  		// d becomes character constant variable

Note: Now the above-declared variables are constant, it means that their values can't be changed during execution of the program.

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