Increment and Decrement Operator in C++


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Increment and Decrement Operator in C++

Increment operators are used to increase the value of the variable by one and decrement operators are used to decrease the value of the variable by one.

Both increment and decrement operator are used on single operand or variable, so it is called as unary operator. Unary operators are having higher priority than the other operators it means unary operators are execute before other operators.

Syntax

 ++  // increment operator
 --   // decrement operator

Note: Increment and decrement operators are can not apply on constant.

Example

x= 4++;  // gives error, because 4 is constant

Type of Increment Operator

  • pre-increment
  • post-increment

pre-increment (++ variable)

In pre-increment first increment the value of variable and then used inside the expression (initialize into another variable).

Syntax

++ variable;

Example pre-increment in C++

#include<iostream.h>
#include<conio.h>

void main()
{
int x,i;
i=10;
x=++i;
cout<<"x: "<<x;
cout<<"i: "<<i;
getch();
}

Output

x: 11
i: 11

In above program first increase the value of i and then used value of i into expression.

post-increment (variable ++)

In post-increment first value of variable is use in the expression (initialize into another variable) and then increment the value of variable.

Syntax

variable ++;

Example post-increment

#include<iostream.h>
#include<conio.h>

void main()
{
int x,i;
i=10;
x=i++;
cout<<"x: "<<x;
cout<<"i: "<<i;
getch();
}

Output

x: 10
i: 11

In above program first used the value of i into expression then increase value of i by 1.

Type of Decrement Operator

  • pre-decrement
  • post-decrement

Pre-decrement (-- variable)

In pre-decrement first decrement the value of variable and then used inside the expression (initialize into another variable).

Syntax

-- variable;

Example pre-decrement

#include<iostream.h>
#include<conio.h>

void main()
{
int x,i;
i=10;
x=--i;
cout<<"x: "<<x;
cout<<"i: "<<i;
getch();
}

Output

x: 9
i: 9

In above program first decrease the value of i and then value of i used in expression.

post-decrement (variable --)

In Post-decrement first value of variable is use in the expression (initialize into another variable) and then decrement the value of variable.

Syntax

variable --;

Example post-decrement

#include<iostream.h>
#include<conio.h>

void main()
{
int x,i;
i=10;
x=i--;
cout<<"x: "<<x;
cout<<"i: "<<i;
getch();
}

Output

x: 10
i: 9

In above program first used the value of x in expression then decrease value of i by 1.

Example of increment and decrement operator

increment and decrement operator

Example

#include<iostream.h>
#include<conio.h>

void main()
{
int x,a,b,c;
a = 2;
b = 4;
c = 5;
x = a-- + b++ - ++c;
cout<<"x: "<<x;
getch();
}

Output

x: 0

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