Thursday, December 31, 2009
PHP Looping For Loops
Loops execute a block of code a specified number of times, or while a specified condition is true.
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The for Loop
The for loop is used when you know in advance how many times the script should run.
Syntax
for (init; condition; increment)
{
code to be executed;
}
Parameters:
• init: Mostly used to set a counter (but can be any code to be executed once at the beginning of the loop)
• condition: Evaluated for each loop iteration. If it evaluates to TRUE, the loop continues. If it evaluates to FALSE, the loop ends.
• increment: Mostly used to increment a counter (but can be any code to be executed at the end of the loop)
Note: Each of the parameters above can be empty, or have multiple expressions (separated by commas).
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
for ($i=1; $i<=5; $i++)
{
echo "The number is " . $i . "<br />";
}
?>
</body>
</html>
Output:
The number is 1
The number is 2
The number is 3
The number is 4
The number is 5
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The foreach Loop
The foreach loop is used to loop through arrays.
Syntax
foreach ($array as $value)
{
code to be executed;
}
For every loop iteration, the value of the current array element is assigned to $value (and the array pointer is moved by one) - so on the next loop iteration, you'll be looking at the next array value.
Example
The following example demonstrates a loop that will print the values of the given array:
<html>
<body>
<?php
$x=array("one","two","three");
foreach ($x as $value)
{
echo $value . "<br />";
}
?>
</body>
</html>
Output:
one
two
three
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