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Looping statements in PHP are used to execute
the same block of code a specified number of times.
Looping
Very often when you write code, you want the same block of
code to run a number of times. You can use looping statements in
your code to perform this.
In PHP we have the following looping statements:
- while - loops through a block of code if and as
long as a specified condition is true
- do...while - loops through a block of code once,
and then repeats the loop as long as a special 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 Statement
The while statement will execute a block of code if and as
long as a condition is true.
Syntax
while (condition)
code to be executed;
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Example
The following example demonstrates a loop that will continue
to run as long as the variable 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>
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The do...while Statement
The do...while statement will execute a block of code at
least once - it then will repeat the loop as long as
a condition is true.
Syntax
do
{
code to be executed;
}
while (condition);
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Example
The following example will increment the value of i at least
once, and it will continue incrementing the variable i as long
as it has a value of less than 5:
<html>
<body>
<?php
$i=0;
do
{
$i++;
echo "The number is " . $i . "<br />";
}
while ($i<5);
?>
</body>
</html>
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The for Statement
The for statement is used when you know how many times you
want to execute a statement or a list of statements.
Syntax
for (initialization; condition; increment)
{
code to be executed;
}
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Note: The for statement has three parameters. The
first parameter initializes variables, the second parameter
holds the condition, and the third parameter contains the
increments required to implement the loop. If more than one
variable is included in the initialization or the increment
parameter, they should be separated by commas. The condition
must evaluate to true or false.
Example
The following example prints the text "Hello World!" five
times:
<html>
<body>
<?php
for ($i=1; $i<=5; $i++)
{
echo "Hello World!<br />";
}
?>
</body>
</html>
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The foreach Statement
The foreach statement is used to loop through arrays.
For every loop, the value of the current array element is
assigned to $value (and the array pointer is moved by one) - so
on the next loop, you'll be looking at the next element.
Syntax
foreach (array as value)
{
code to be executed;
}
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Example
The following example demonstrates a loop that will print the
values of the given array:
<html>
<body>
<?php
$arr=array("one", "two", "three");
foreach ($arr as $value)
{
echo "Value: " . $value . "<br />";
}
?>
</body>
</html>
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