The value of the condition is tested first in the while loop , then the loop body is executed only if the condition is true. But for the initial value of the do ... while loop counter variable, the loop body is first performed once and then the condition value is tested. That is, if the condition is not true, the statement associated with the while loop is not executed. But even if the condition is true, the statement associated with the do ... while loop is executed at least once. Therefore, when a soup must be performed at least once , a do ... while loop is used. Additionally , an additional semicolon ( ;) is used at the end of the do ... while loop header line.