The Perl for loop is used to execute a sequence of statements multiple times, simplifying the code that manages loop variables.
The syntax format is as follows:
for ( init; condition; increment ){ statement(s);}The following is the control flow analysis of the for loop:
init will be executed first and only once. This step allows you to declare and initialize any loop control variables. You can also write no statement here, as long as a semicolon appears.
Next, the condition will be judged. If true, the loop body is executed. If false, the body of the loop is not executed and control flow jumps to the next statement immediately following the for loop.
After executing the for loop body, the control flow will jump back to the increment statement above. This statement allows you to update loop control variables. The statement can be left blank as long as a semicolon appears after the condition.
The condition is evaluated again. If it is true, the loop is executed and the process is repeated (loop body, then increasing the step value, and then re-judging the condition). The for loop terminates when the condition becomes false.
Here, statement(s) can be a single statement or a block of code composed of several statements.
condition can be any expression. When the condition is true, the loop is executed. When the condition is false, the loop is exited.
Executing the above program, the output result is:
The value of a is: The value of 0a is: The value of 1a is: The value of 2a is: The value of 3a is: The value of 4a is: The value of 5a is: The value of 6a is: The value of 7a is: The value of 8a is: 9