The use of function is similar to other language functions, take one or more parameters as input, process and provide the corresponding result. The block of code to be used more frequently is added inside the functions. The execution of function is dependent on two points as create the function and call the function. PHP function creation The function keyword is used for the function creation. The code is added inside the curly braces. Syntax of function creation Code: function FunctionName() { Code to be executed; } User can start the function name using a letter or underscore. A number cannot be used for function declaration. Example: Code: <html> <body> <?php /* function definition*/ function display(){ echo "Welcome User"; } /*Call the function */ display(); ?> </body> </html> Function with parameters User can pass the parameters to the PHP functions. The parameters are used as variables. They are defined following the function name, places inside the parentheses. More than one parameter can be added by using comma. Code: <html> <body> <?php function multiplyno ( $no1, $no2) { $result = $no1 * $no2; echo "Multiplication of two numbers is : $result"; } multiplyno ( 5, 10 ); ?> </body> </html> If we don't need to pass the variable values each time a function is called, we can use default values for parameters. The default parameters are the last parameters. Code: <html> <body> <?php function multiplyno ( $no1, $no2 = 2) { $result = $no1 * $no2; echo "Multiplication of two numbers is : $result"; } multiplyno ( 5, 10 ); multiplyno ( 5 ); // Takes second argument as 2 ?> </body> </html> Passing with reference User can pass the values as reference to the functions. The variables are referred using the ampersand sign before the variable name. The modifications to the argument are reflected to the value of the variable. Example: Code: <html> <body> <?php function increaseno ( &$no ) { $no + = 1; } $num = 2; increaseno ( $num ); echo "The number is $num"; ?> </body> </html> Function returning values In PHP, the return keyword is used for returning the value from the functions. More than one value can be returned from a function. Example: Code: <html> <body> <?php function multiply( $no1, $no2) { $result = $no1 * $no2; return $result; } $output = multiply ( 2, 5 ); echo "The value after computing the function is: $output"; ?> </body> </html> Dynamic function calls User can use the function names as the strings. The variables on which it is assigned are used as function name. Example: Code: <html> <body> <?php function UserWelcome() { echo "Welcome<br/>"; } $function_id = "UserWelcome"; $function_id(); ?> </body> </html>
