The increment operator can appear before or after a variable. Both forms increase the variable by 1, but they differ in the value produced when the operation is used inside an expression.

#include <stdio.h>

int main()
{
    int a = 5;
    int b = 5;

    printf("Pre-increment: %d\n", ++a);
    printf("Post-increment: %d\n", b++);

    printf("a = %d\n", a);
    printf("b = %d\n", b);

    return 0;
}

Example Output #

Pre-increment: 6
Post-increment: 5
a = 6
b = 6

Explanation #

In pre-increment:

++a

a is incremented before its value is used by the expression. Therefore, ++a produces 6.

In post-increment:

b++

the original value of b is used by the expression first. The increment is then applied, so the expression produces 5, while b becomes 6.

Both forms ultimately increase the variable by 1; the difference is the value produced by the expression.