C++ Variables

Variables in C++ can be used to store data in the memory location and whose value can be changed during the program execution.

In C++ variables are case sensitive. They can be represented using letters, digits, and underscore.

Rules for Declaring variables in C++

If you want to declare any variables in C++, we just need to follow some rules. They are as follows:

The first character must be a letter (or) underscore.
Blank spaces cannot be used in variable names.
A variable name consists of uppercase, lower case, numbers.
Special characters like #, $ are not allowed.
C++ keywords cannot be used as names.
And all the names are case sensitive.
The variable name consists of 31 characters only if we declare the variable more than one character, the compiler will ignore after 31 characters.
variable types can be bool, char, int, float, double, void, wchar_1.

C++ Variables Example:

#include <iostream>
using namespace std;
// Variable declaration:
extern int a, b;
extern int c;
extern float f; 
int main () {
//Variable definition:
int a, b;
int c;
float f;
//actual initialization
a = 10;
b = 20;
c = a + b; 
cout<<c<<endl ;
f=70.0/3.0;
cout << f << endl ;
return 0;
}

Output:

30
23.3333

Variable Definition in C++

A variable definition in C++ is nothing but it defines when a programmer writes some instructions to tell the compiler to create the storage in the memory location.

Syntax: data_type variable_name;

Here data_type means it includes int, float, double, char, wchar_t, bool.

Example:

int    width,height,age;/*variable definition*/
char   letter;
float  area;
double d;

Variable Declaration in C++

Variable initialization in C++ is nothing but the variable values can be assigned and the initial values can be assigned along with their declaration.

Syntax: data_type variable_name = value;

Example:

int width,height=5,age=32;/*variable definition and initialization*/
char letter='A';
float area;
double d;
/*actual initialization*/
width = 10;
area = 26.5;