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PHP Functions

The real power of PHP comes from its functions.

In PHP, providing more than 1000 built-in functions.


PHP built-in function

For a complete reference manual and all instances of array functions, visit our PHP Reference .


PHP Functions

In this chapter, we will show you how to create your own functions.

To run the script when the page loads, you can put it in the function.

Function is performed by calling the function.

You can call a function in any position on the page.


Create a PHP Function

Function is performed by calling the function.

grammar

functionfunctionName()
{
要执行的代码;
}

PHP function guidelines:

  • The name of the function should prompt its function
  • Function names begin with a letter or an underscore (can not start with a number)

Examples

A simple function when it is invoked my name can be output:

<html>
<body>

<?php
function writeName()
{
echo "Kai Jim Refsnes";
}

echo "My name is ";
writeName();
?>

</body>
</html>

Output:

My name is Kai Jim Refsnes


PHP Functions - Adding parameters

In order to add more functionality to a function, we can add parameters. Similar arguments variable.

Parameters after the function name has a designated parenthesis.

Example 1

The following examples will output a different name, but the name is the same:

<html>
<body>

<?php
function writeName($fname)
{
echo $fname . " Refsnes.<br>";
}

echo "My name is ";
writeName("Kai Jim");
echo "My sister's name is ";
writeName("Hege");
echo "My brother's name is ";
writeName("Stale");
?>

</body>
</html>

Output:

My name is Kai Jim Refsnes.
My sister's name is Hege Refsnes.
My brother's name is Stale Refsnes.

Example 2

The following function has two parameters:

<html>
<body>

<?php
function writeName($fname,$punctuation)
{
echo $fname . " Refsnes" . $punctuation . "<br>";
}

echo "My name is ";
writeName("Kai Jim",".");
echo "My sister's name is ";
writeName("Hege","!");
echo "My brother's name is ";
writeName("Stale","?");
?>

</body>
</html>

Output:

My name is Kai Jim Refsnes.
My sister's name is Hege Refsnes!
My brother's name is Stale Refsnes?

PHP Functions - Return Value

To make the function returns a value, use the return statement.

Examples

<html>
<body>

<?php
function add($x,$y)
{
$total=$x+$y;
return $total;
}

echo "1 + 16 = " . add(1,16);
?>

</body>
</html>

Output:

1 + 16 = 17