for Loops

for Loops

The for loop is another excellent control statement tool. The basic syntax of a for loop follows:

for ([initial condition]; [test]; [incrementation])
       {
       [action to perform]
       }

The "initial condition" defines where the loop should begin. The "test" defines the logic of the loop by letting the script know the conditions that determine the scripts actions. The "incrementation" defines how the script should perform the loop. For example, we might produce a visible countdown with the following for loop:

for ($number = 10; $number >= 0; $number--)
       {
       print "$number\n";
       }

The script would initially assign "10" to the scalar variables $number. It would then test to see if $number was greater than or equal to zero. Since ten is greater than zero, the script would decrement $number by subtracting one from the value of $number.

To decrement, you use $variable_name--. To increment, you use $variable_name++.

Executing the statement block, the script would then print out the number nine. Then, it would go back through the loop again and again, printing each decremented numbers until $number was less than zero. At that point, the test would fail and the for loop would exit.

while
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Using logical operators (&& and ||)