Omitting Parts of the for

Parts of a for can be omitted. Since the three parts of a for are the three parts of any loop, when a part is eliminated from a for it has to be made up elsewhere. Recall that the for is equivalent to a while:

for ( initialize ; test ; change )
  loopBody ;

initialize;
while ( test )
{
  loopBody;
  
  change
}

You can omit the initialize part from the for loop. It now acts the same as a while loop with its initialize part omitted. Doing this is useful when initialization is complicated and you wish to do it in several statements before the loop. For example, initialization may depend on user input:

    // get initial value of count from the user here

    for (    ; count < 13; count++  )  
    {
      System.out.println( "count is: " + count ); 
    }
    System.out.println( "\nDone with the loop.\nCount is now" + count);

Here is a Javascript simulation of this: