C++ Increment and Decrement Operators

The increment (++) and decrement (--) operators in C++ are unary operators used to increase or decrease the value of a variable by 1. These operators are commonly used in loops, counters, and iterator operations.

• ++ increases the value of a variable by 1.
• -- decreases the value of a variable by 1.

Increment Operator in C++

The increment operator (++) increases the value stored in a variable by 1.

• It is a unary operator.
• It can be used only with modifiable numeric variables.

There are two types of increment operators:

Post-Increment operator (a++)

The postfix operator says that first use the value and then increment it. This means the value is first used for the operation and then increased by 1.

#include <iostream>
using namespace std;

int main()
{

    int x = 5;
    cout << "Value before using post increment operator is "
            ": "
         << x << endl;
    int temp = x++;
    cout << "The value stored by temp is : " << temp
         << endl;
    cout << "After using the post increment operator is : "
         << x << endl;
    return 0;
}

Value before using post increment operator is : 5
The value stored by temp is : 5
After using the post increment operator is : 6

Explanation: The value of x is first assigned to temp, after which x is incremented by 1.

Pre-increment operator(++a)

The prefix operator says that first increment the value and then use it. This means the value is increased by 1 before it is used in the expression.

#include <iostream>
using namespace std;

int main()
{

    int x = 5;
    cout
        << "Value before using pre increment operator is : "
        << x << endl;
    int temp = ++x;
    cout << "The value stored by temp is : " << temp
         << endl;
    cout << "After using the post increment operator is : "
         << x << endl;
    return 0;
}

Value before using pre increment operator is : 5
The value stored by temp is : 6
After using the post increment operator is : 6

Explanation: The value of x is incremented first and then assigned to temp.

Decrement Operator in C++

The decrement operator (--) decreases the value stored in a variable by 1.

• It is a unary operator.
• It can be used only with modifiable numeric variables.

There are two types of decrement Operator:

Post-decrement operator (a--)

The postfix operator says that first use the value and then decrement it. This means the value is first used for the operation and then decreased by 1.

#include <iostream>
using namespace std;

int main()
{

    int x = 5;
    cout << "Value before using post decrement operator is "
            ": "
         << x << endl;
    int temp = x--;
    cout << "The value stored by temp is : " << temp
         << endl;
    cout << "After using the post decrement operator is : "
         << x << endl;
    return 0;
}

Value before using post decrement operator is : 5
The value stored by temp is : 5
After using the post decrement operator is : 4

Explanation: The current value of x is assigned to temp, after which x is decreased by 1.

Pre-decrement operator (--a)

The prefix operator says that first decrement the value and then use it. This means the value is decreased by 1 before it is used in the expression.

#include <iostream>
using namespace std;

int main()
{

    int x = 5;
    cout
        << "Value before using pre-decrement operator is : "
        << x << endl;
    int temp = --x;
    cout << "The value stored by temp is : " << temp
         << endl;
    cout << "After using the pre-decrement operator is : "
         << x << endl;
    return 0;
}

Value before using pre-decrement operator is : 5
The value stored by temp is : 4
After using the pre-decrement operator is : 4

Explanation: The value of x is decremented first and then assigned to temp.

Pre Vs Post Operators