This section provides a tutorial example on how to use 'for' statements to repeatedly execute zero, one or more statements.
To help us understand how "for" statements work, I wrote the following the tutorial example script:
<?php # ForStatements.php
# Copyright (c) 2003 by Dr. Herong Yang. http://www.herongyang.com/
#
$upperLimit = 20;
#
print("\n No-statement \"for\":\n");
for ($sum = 0, $i = 0; $i<$upperLimit; $sum += ++$i);
print(" Sum of 1 to 20: $sum\n");
print("\n Single-statement \"for\":\n");
for ($sum = 0, $i = 0; $i<$upperLimit; $i++) $sum += $i;
print(" Sum of 0 to 19: $sum\n");
#
print("\n Multi-statement \"for\":\n");
for ($i=3; $i<$upperLimit; $i++) {
$isPrime = true;
for ($j=2; $j<=$i/2; $j++) {
$isPrime = $i%$j > 0;
if (!$isPrime) break;
}
if ($isPrime) print " $i is a prime number.\n";
}
#
print("\n Multi-statement \"for ... endfor\":\n");
for ($i=3; $i<$upperLimit; $i++):
$isPrime = true;
for ($j=2; $j<=$i/2; $j++):
$isPrime = $i%$j > 0;
if (!$isPrime) break;
endfor;
if ($isPrime) print " $i is a prime number.\n";
endfor;
?>
If you run this sample script, you should get:
No-statement "for":
Sum of 1 to 20: 210
Single-statement "for":
Sum of 0 to 19: 190
Multi-statement "for":
3 is a prime number.
5 is a prime number.
7 is a prime number.
11 is a prime number.
13 is a prime number.
17 is a prime number.
19 is a prime number.
Multi-statement "for ... endfor":
3 is a prime number.
5 is a prime number.
7 is a prime number.
11 is a prime number.
13 is a prime number.
17 is a prime number.
19 is a prime number.
