Pre- vs Post- increment/decrement

The difference between ++x and x++

The important distinction between Pre- and Post- increment/decrement operators is in the “return value” of the operator. Both ++x and x++ have the same side-effect; the value of x will go up by 1 when the statement runs. However, if you read the value returned by the operator, ++x will read the value AFTER it goes up by 1, and x++ will read the value BEFORE it goes up by 1.

int x = 5;
Trace(x++); // prints '5'
Trace(x);   // prints '6'
int y = 2;
Trace(++y); // prints '3'
Trace(y);   // prints '3'

Note

One of the most common places you’ll see these operators, is in the increment part of a for loop. When it is there, generally the operator’s “return value” is ignored, so it does not matter which you use.