Functions are the tasks or actions that software is intended to perform.They are blocks of reusable
code that can be passed parameters and can return a value.
For example, the getAddress function is passed the name of a property and and it returns
the address of that name. The getVersion function returns the version of the Flash Player currently playing the movie.
You can also find a huge list of predefined functions built into PHP in the PHP Manual's function reference
Declaring a function in PHP
The word "function" is a reserved keyword to tell the parser you are declaring a function.
The function is given a name (here func_name). You may use any name you wish that starts with a letter, and is not a reserved word or an existing function.
Functions often have parameters that operate similarly to variables.
<?php
function func_name(parameters)
{
//statements
}
?> |
Functions with Parameters
Parameters are variables that exist only within that function. They are provided by the programmer when the function is called .
When declaring or calling a function that has more than one parameter, you need to separate between different parameters with a comma ','.
<?php
function Two_Names($name1, $name2)
{
echo $name1;
echo "\n";
echo $name2;
return NULL;
}
?> |
To call this function you must give the parameters a value. It doesn't matter what the value it, as long as there is one.
function call:
<?php
Two_Names("paul", "Joseph");
?> |
Output:
You can pass the values to the parameters when declaring a function , it will act as a default parameter value.
<?php
function Two_Names($name1 = "john", $name2 = "joseph")
{
echo($name1);
echo("\n");
echo($name2);
}
?> |
function call:
<?php
Two_Names("hello", "Joseph");
?> |
Output:
Functions with Returning a value
This function is all well and good, but usually you will want your function to return some information
To return a value from a function use the return() statement in the function.
<?php
function Findsum($var1 = 0, $var2 = 0, $var3 = 0)
{
$var4 = $var1 + $var2 + $var3;
return $var4;
}
?> |
function call:
<?php
$sum = Findsum(10,20,30);
echo "sum = ".$sum;
?> |
Output:
