"for" Statement Examples

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) HerongYang.com. All Rights Reserved.
#
\$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:

```C:\herong> \php\php ForStatements.php

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.
```

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