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PHP Looping - While Loops
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Loops execute a block of code a specified number of times, or while a specified condition is true.
PHP Loops
Often when you write code, you want the same block of code to run over and over again in a row. Instead of adding several almost equal lines in a script we can use loops to perform a task like this.
In PHP, we have the following looping statements:
- while - loops through a block of code while a specified condition is true
- do...while - loops through a block of code once, and then repeats the loop as long as a specified condition is true
- for - loops through a block of code a specified number of times
- foreach - loops through a block of code for each element in an array
The while Loop
The while loop executes a block of code while a condition is true.
Syntax
| while (condition) { code to be executed; } |
Example
The example below defines a loop that starts with i=1. The loop will continue to run as long as i is less than, or equal to 5. i will increase by 1 each time the loop runs:
| <html> <body> <?php $i=1; while($i<=5) { echo "The number is " . $i . "<br />"; $i++; } ?> </body> </html> |
Output:
| The number is 1 The number is 2 The number is 3 The number is 4 The number is 5 |
The do...while Statement
The do...while statement will always execute the block of code once, it will then check the condition, and repeat the loop while the condition is true.
Syntax
| do { code to be executed; } while (condition); |
Example
The example below defines a loop that starts with i=1. It will then increment i with 1, and write some output. Then the condition is checked, and the loop will continue to run as long as i is less than, or equal to 5:
| <html> <body> <?php $i=1; do { $i++; echo "The number is " . $i . "<br />"; } while ($i<=5); ?> </body> </html> |
Output:
| The number is 2 The number is 3 The number is 4 The number is 5 The number is 6 |
The for loop and the foreach loop will be explained in the next chapter.
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