What is the difference between ++i and i++?

Question

In C, what is the difference between using `++i` and `i++`, and which should be used in the incrementation block of a `for` loop?

Answer 1

i++ is called post-increment and ++i is pre-increment. There is no difference as far as the final value of i is concerned, but there is a major difference in other parts of the statement that may use i. Consider this code snippet:

i = 10;

j = i++;

k = ++i;

With post-increment, the value of the variable is evaluated before the increment happens. So, in the second statement, i is evaluated as 10 and j gets that value, THEN i is incremented to 11.

In the third statement, pre-incrementing means the variable is incremented before the value is evaluated. So i is incremented to 12 and then k gets the new value of 12 instead of the old value of 11.