"while" Statement Examples

This section provides a tutorial example on how to use 'while' statements to repeat execution of one or more statements while a specified condition is true.

To help us understand how "while" statements work, I wrote the following the tutorial example PHP script:

```<?php # WhileStatements.php
#
\$upperLimit = 20;
#
print("\n Single-statement \"while\":\n");
\$sum = 0; \$i = 0;
while (\$i<\$upperLimit) \$sum += ++\$i;
print("    Sum of 1 to 20: \$sum\n");
#
print("\n Multi-statement \"while\":\n");
\$i = 3;
while (\$i<\$upperLimit) {
\$isPrime = true;
\$j = 2;
while (\$j<\$i) {
\$isPrime = \$i%\$j > 0;
if (!\$isPrime) break;
\$j++;
}
if (\$isPrime) print "   \$i is a prime number.\n";
\$i++;
}
#
print("\n Multi-statement \"while ... endwhile\":\n");
\$i = 3;
while (\$i<\$upperLimit):
\$isPrime = true;
\$j = 2;
while (\$j<\$i):
\$isPrime = \$i%\$j > 0;
if (!\$isPrime) break;
\$j++;
endwhile;
if (\$isPrime) print "   \$i is a prime number.\n";
\$i++;
endwhile;
?>
```

If you run this sample script, you should get:

``` Single-statement "while":
Sum of 1 to 20: 210

Multi-statement "while":
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 "while ... endwhile":
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.
```

Last update: 2015.