A for statement has the form
This works as follows. First statement1 is executed. Then the expression is evaluated. If it is true, statement 3 is executed; then statement 2 and then the expression is evaluated again. This continues until the expression is false.
This may sound complicated. You should interpret this as follows. The first statement initializes the for-loop. The expression tests whether the loop should be ended. Statement2 is the step statement that goes to the next loop evaluation.
The most common use is to have a counter run through some range.
The following program initializes an array of length 10 with the values 1 - 10.
for (i=0; i<=9; i+=1) list[i] = i+1;
Contributor: Mark Overmars