Functions in PHP

Functions in PHP - In the world of programming, in any language, the use of a function is absolute, therefore it is important to learn it. The function in the programming language is the program code designed to accomplish a specific task, and is part of the main program.
There are several main things to note in the function declaration in PHP.

• Function name
• Parameters
• Function body

Regarding this function there are two main things we can do, namely:

• Defines its own function, if the function we want has not been provided by PHP
• Call function, both built-in function and user-defined function how to call it the same ie write the name of the function then followed by parentheses, for example we call the print function, then we write: print ()

The general form of function defining in PHP
function Function_name (parameter1,...,n) {
statement2; 
}
To better understand it, here I give examples of program functions in php.
Program 1
File Name: function01.php
Description: A simple program defines and invokes functions without parameters and without return value.
Open notepad, then type the following php code.
<?php
function odd_print () {
 for ($i=0; $i<100; $i++) {
  if ($i%2 == 1) {
   echo "$i "; 
}
}
}
//Function call
odd_print();
?>

Save the php code in the htdocs folder named function01.php.
To see the result, open the browser type http://localhost/function01.php in the address bar then enter. Then the result will look like the following.

Program view

Program 2
File Name: function02.php
Description: Program function with parameters.
<?php
function odd_print ($early, $end) {
 for ($i=$early; $i<$end; $i++) {
  if ($i%2 == 1) {
   echo "$i "; 
}
}
}
//Function call
$a = 10;
$b = 50;
echo "<b>An odd number from $a to $b : </b><br>";
odd_print($a, $b);
?>

Program view

Program 3
File Name: function03.php
Description: Program function that returns a value.
<?php
function wide_circle ($radius) {
 return 3.14 * $radius * $radius;
}
//Function call
$r = 10;
echo "Broad circle with radius $r = ";
echo wide_circle($r);
?>

Program view

Program 4
File Name: function04.php
Description: Program passing value in function.
<?php
function added_string ($str) {
 $str = $str . ", Madison";
return $str;
}
//
$str = "University of Wisconsin";
echo "\$str = $str<br>";
echo added_string ($str). "<br>";
echo "\$str = $str<br>";
?>

Program view

Program 5
File Name: function05.php
Description: Program passing by reference in function.
<?php
function added_string (&$str) {
 $str = $str . ", Madison";
return $str;
}
//
$str = "University of Wisconsin";
echo "\$str = $str<br>";
echo added_string ($str). "<br>";
echo "\$str = $str<br>";
?>

Program view

Program 6
File Name: function06.php
Description: The program displays the defined-function supported by PHP.
<?php
function wide_circle ($radius) {
 return 3.14 * $radius * $radius;
}
$arr = get_defined_functions();
echo "<pre>";
print_r($arr);
echo "</pre>";
?>

Program view

Program 7
File Name: function07.php
Description: Program checks a function available in PHP or not.
<?php
if (function_exists('exif_read_data')) {
echo "Function exif_read_data() Is in PHP.<br />\n";
} else {
echo "Function exif_read_data() Not in PHP.<br />\n";
}
?>

Program view

That's the article that I can explain about Functions in PHP, hopefully can increase our knowledge of php programming language. Learn also articles about Array Functions Examples in PHP.