What is the way to write php function?

The writing method of php function is "<?php function functionName(){...}". The name of the function should indicate its function, and the function name should start with a letter or an underscore.

The operating environment of this article: windows7 system, PHP7.1 version, DELL G3 computer

PHP function

The real power of PHP comes from its functions.

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

PHP Built-in Functions

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

PHP Functions

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.

Creating PHP functions

Functions are executed by calling functions.

Syntax

<?php
function functionName()
{
    // 要执行的代码
}
?>

PHP function guidelines:

The name of the function should indicate its function

The function name starts with a letter or Starts with an underscore (cannot start with a number)

Example

A simple function that prints my name when called:

Example

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

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

Output:

My name is Kai Jim Refsnes

PHP Function - Add Parameters

In order to add more functions to the function, we can add parameters, which are similar to variables.

The parameters are specified within a bracket after the function name.

Example 1

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

Example

<?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");
?>

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:

Example

<?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("Ståle","?");
?>

Output:

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

PHP function - return value

If you need the function to return a value, please use the return statement.

Example

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

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

Output:

1 + 16 = 17

Recommended learning: "PHP Video Tutorial"

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