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php function, php function manual

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Release： 2016-07-06 14:25:19

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php functions, php function manual

The real power of PHP comes from its functions.

In PHP, more than 1000 built-in functions are provided.

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

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

Functions are executed by calling functions.

You can call functions anywhere on the page.

Create PHP function

Functions are executed by calling functions.

Grammar

<span>function</span><span> functionName()
{
要执行的代码;
}</span>

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PHP Function Guidelines:

The name of the function should indicate its function
Function name starts with a letter or underscore (cannot start with a number)

Example

A simple function that prints my name when called:

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

</span><span>echo</span> "My name is "<span>;
writeName();
</span>?>

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Output:

My name is Kai Jim Refsnes

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PHP Function - Add Parameters

In order to add more functionality to the function, we can add parameters. Parameters are like variables.

The parameters are specified in parentheses just after the function name.

Example 1

The following example will output different first names, but the same last name:

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

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

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Output:

My name is Kai Jim Refsnes.<span>
My sister</span>'<span>s name is Hege Refsnes.
My brother</span>'s name is Stale Refsnes.

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Example 2

The following function has two parameters:

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

</span><span>echo</span> "My name is "<span>;
writeName(</span>"Kai Jim","."<span>);
</span><span>echo</span> "My sister's name is "<span>;
writeName(</span>"Hege","!"<span>);
</span><span>echo</span> "My brother's name is "<span>;
writeName(</span>"St&aring;le","?"<span>);
</span>?>

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PHP function - return value

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

Example

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

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

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Output: