Top-driven Loop

Here is the example for loop and its equivalent while loop:

int count, sum;
sum = 0;

for ( count = 0; count <= 5; count++ )
{
  sum = sum + count ;
  System.out.print( count + " " );
}

System.out.println( "sum is: " + sum );

int count, sum;
sum   = 0;
count = 0;

while ( count <= 5 )
{
  sum = sum + count ;
  System.out.print( count + " " );
  count++ ;
}

System.out.println( "sum is: " + sum );

Notice two important aspects of these loops:

1. The test is performed every time, just before execution is about to enter the loop body.
2. The change is performed at the bottom of the loop body, just before the test is re-evaluated.

Loops that work this way are called top-driven loops, and are usually mentally easier to deal with than other arrangements.

Look back at the loop flow chart loop flow chart to see this graphically.