• php
  • 1708
  • 20-3-2008
    • [L]The real power of PHP comes from its functions.
    In PHP - there are more than 700 built-in functions available.
    --------------------------------------------------------------------------------
    PHP Functions
    In this tutorial we will show you how to create your own functions.
    --------------------------------------------------------------------------------
    Create a PHP Function
    A function is a block of code that can be executed whenever we need it.
    Creating PHP functions:
    - All functions start with the word "function()"
    - Name the function - It should be possible to understand what the function does by its name. The name can start with a letter or underscore (not a number)
    - Add a "{" - The function code starts after the opening curly brace
    - Insert the function code
    - Add a "}" - The function is finished by a closing curly brace
    Example
    A simple function that writes my name when it is called:
    <html>
    
<body>
    
<?php
    
function writeMyName()
    
  {
    
  echo "Kai Jim Refsnes";
    
  }writeMyName();
    
?>
    
</body>
    
</html>

    --------------------------------------------------------------------------------
    Use a PHP Function
    Now we will use the function in a PHP script:
    <html>
    
<body>
    
<?php
    
function writeMyName()
    
  {
    
  echo "Kai Jim Refsnes";
    
  }echo "Hello world!<br />";
    
echo "My name is ";
    
writeMyName();
    
echo ".<br />That's right, ";
    
writeMyName();
    
echo " is my name.";
    
?>
    
</body>
    
</html>

    The output of the code above will be:
    Hello world!
    
My name is Kai Jim Refsnes.
    
That's right, Kai Jim Refsnes is my name.

    --------------------------------------------------------------------------------
    PHP Functions - Adding parameters
    Our first function (writeMyName()) is a very simple function. It only writes a static string.
    To add more functionality to a function, we can add parameters. A parameter is just like a variable.
    You may have noticed the parentheses after the function name, like: writeMyName(). The parameters are specified inside the parentheses.
    Example 1
    The following example will write different first names, but the same last name:
    <html>
    
<body>
    
<?php
    
function writeMyName($fname)
    
  {
    
  echo $fname . " Refsnes.<br />";
    
  }echo "My name is ";
    
writeMyName("Kai Jim");echo "My name is ";
    
writeMyName("Hege");echo "My name is ";
    
writeMyName("Stale");
    
?>
    
</body>
    
</html>

    The output of the code above will be:
    My name is Kai Jim Refsnes.
    
My name is Hege Refsnes.
    
My name is Stale Refsnes.

    Example 2
    The following function has two parameters:
    <html>
    
<body>
    
<?php
    
function writeMyName($fname,$punctuation)
    
  {
    
  echo $fname . " Refsnes" . $punctuation . "<br />";
    
  }echo "My name is ";
    
writeMyName("Kai Jim",".");echo "My name is ";
    
writeMyName("Hege","!");echo "My name is ";
    
writeMyName("St&aring;le","...");
    
?>
    
</body>
    
</html>

    The output of the code above will be:
    My name is Kai Jim Refsnes.
    
My name is Hege Refsnes!
    
My name is St&aring;le Refsnes...


    --------------------------------------------------------------------------------
    PHP Functions - Return values
    Functions can also be used to return values.
    Example
    <html>
    
<body>
    
<?php
    
function add($x,$y)
    
  {
    
  $total = $x + $y;
    
  return $total;
    
  }echo "1 + 16 = " . add(1,16)
    
?>
    
</body>
    
</html>

    The output of the code above will be:
    1 + 16 = 17
    [/L]
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