There are subtle differences between how that value of the counter is incremented when it is prefixed (++ comes before the expression is evaluated) or postfixed (++ comes after the expression).
In prefix notation, ++ is applied to the result of the expression before its value is considered. In postfix notations, the result of the expression is applied to any other evaluation and then the ++ operation is performed.
Here, an example will be useful.
In this example, we set a value and then print that value using both the prefix and postfix notations. Finally, the program shows a more predictable method. That is, perform either method of incrementation as a single statement. The result will always be what we expect:
int main( void )
{
int aValue = 5;
// Demonstrate prefix incrementation.
printf( "Initial: %d\n" , aValue );
printf( " Prefix: %d\n" , ++aValue ); // Prefix incrementation.
...