Functions are used to reduce the repetition of codes in your scripts.
The user define function are starts with function tag.
The function name should not start with numbers ( 0 – 9 ). The allowed format is letters ( a-z, A-Z ) and underscores ( _ ).
Beginning with curly braces ( { ) indicates the function get start to execute the block of code under the function. Closing curly braces ( } ) indicates the closing / end of the function.
<?php function cityDetails($city){ echo "Am staying in $city"; echo "<br />"; } cityDetails("New York"); cityDetails("Los Angeles"); ?> Output: Am staying in New York Am staying in Los Angeles
<?php function add($a,$b){ $c = $a + $b; return $c; } function sub($a,$b){ $c = $a - $b; return $c; } function mul($a,$b){ $c = $a * $b; return $c; } $addingValues = add(25,15); $subtractingValues = sub(30,10); $multiplicationValues = mul($addingValues,$subtractingValues); echo "Multiplication Value is :: $multiplicationValues"; ?> Output : Multiplication Value is :: 800 // addition value is 40 // subtraction value is 20 // Multiplication of both the data will be 40 * 20 = 800
For more info please refer php.net functions section.