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 code-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 as long as the specified condition is true
- do...while - loops through a block of code once, and then repeats the loop as long as the 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 PHP while Loop
The while loop executes a block of code as long as the specified condition is true.
Example
<html>
<body>
<?php
$x=1;
while($x<=5)
{
echo "The number is: $x <br>";
$x++;
}
?>
</body>
</html>
<body>
<?php
$x=1;
while($x<=5)
{
echo "The number is: $x <br>";
$x++;
}
?>
</body>
</html>
The PHP do...while Loop
The do...while loop will always execute the block of code once, it will then check the condition, and repeat the loop while the specified condition is true.
Example
<html>
<body>
<?php
$x=1;
do
{
echo "The number is: $x <br>";
$x++;
}
while ($x<=5)
?>
</body>
</html>
<body>
<?php
$x=1;
do
{
echo "The number is: $x <br>";
$x++;
}
while ($x<=5)
?>
</body>
</html>
The PHP for Loop
The for loop is used when you know in advance how many times the script should run.
Parameters:
- init counter: Initialize the loop counter value
- test counter: Evaluated for each loop iteration. If it evaluates to TRUE, the loop continues. If it evaluates to FALSE, the loop ends.
- increment counter: Increases the loop counter value
Example
<html>
<body>
<?php
for ($x=0; $x<=10; $x++)
{
echo "The number is: $x <br>";
}
?>
</body>
</html>
<body>
<?php
for ($x=0; $x<=10; $x++)
{
echo "The number is: $x <br>";
}
?>
</body>
</html>
The PHP foreach Loop
The foreach loop works only on arrays, and is used to loop through each key/value pair in an array.
Example
<html>
<body>
<?php
$colors = array("red","green","blue","yellow");
foreach ($colors as $value)
{
echo "$value <br>";
}
?>
</body>
</html>
<body>
<?php
$colors = array("red","green","blue","yellow");
foreach ($colors as $value)
{
echo "$value <br>";
}
?>
</body>
</html>
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