A function is a piece of code that takes another input in the form of a parameter, processes it, and then returns a value. A PHP Function feature is a piece of code that can be used over and over again and accepts argument lists as input, and returns a value. PHP comes with thousands of built-in features.
Built-in Functions in PHP
PHP has over 1000 built-in functions that can be called directly from within a script to perform a specific task in PHP Functions.
User Defined Functions in PHP
- In PHP, functions can be written on their own in addition to the built-in PHP functions.
- A function is a set of statements that can be used repeatedly in a program.
- When a page loads, a feature will not run automatically.
- A call to a function will cause it to be executed.
Advantages of PHP Function
- Reusability of Code: Unlike other programming languages, PHP Functions are specified only once and can be called multiple times.
- Less Code: It saves a lot of code because the logic doesn't have to be written several times. You can write the logic only once and reuse it by using functions.
- Simple to Comprehend: The programming logic is separated using PHP Functions. Since every logic is divided into functions, it is easier to understand the application's flow.
Creating and Calling Function
In PHP, the function name is any name that ends in an open and closed parenthesis.
- The keyword function is often used to start a function name.
- To invoke a function, simply type its name followed by the parenthesis.
- A number cannot be the first character in a feature name. It can begin with a letter or an underscore.
- The case of a feature name is unimportant.
Syntax:
function function_name()
{
//Statement to be executed
}
Code:
<!DOCTYPE html>
<html>
<body>
<?php
functionwelcMsg()
{
echo "Hello welcome!";
}
welcMsg();
?>
</body>
</html>
<!DOCTYPE html>
<html>
<body>
<?php
functionwelcMsg()
{
echo "Hello welcome!";
}
welcMsg();
?>
</body>
</html>
Explanation:
In the above example, a function called "welcMsg()" is created. The beginning of the function code is indicated by the opening curly bracket {, and the end of the function is indicated by the closing curly bracket }. The function says "Hello welcome!"; write the function's name in brackets () to invoke it.
Output:
PHP Function Arguments
In PHP Function, arguments may be used to transfer information to functions. A variable is the same as an argument. Arguments are listed within parentheses after the function name. You can add as many arguments as you want; just use a comma to divide them.
Parameters are the information or variables contained within the function's parenthesis. These are used to store the values that can be executed at runtime. A user can enter as many parameters as he desires, separated by the comma (,) operator. During runtime, these parameters are used to accept inputs. Arguments are used while exchanging values, such as during a function call.
Code:
<!DOCTYPE html>
<html>
<body>
<?php
functionStudentsName($firstname)
{
echo "$firstname<br>";
}
StudentsName("Janani");
StudentsName("Helen");
StudentsName("Stella");
StudentsName("Kamal");
StudentsName("Babu");
?>
</body>
</html>
Explanation:
A function with only one argument ($fname) is used in the following example. When we call the StudentsName() function, we also transfer a name (for example, Janani) used within the function to generate several different first names but the same last name.
Output:
Passing Arguments By Reference
Arguments are generally passed by value in PHP, which ensures that the function uses a copy of the value and the variable passed into the function cannot be modified. Changes to the argument modify the variable passed in when a function argument is passed by reference. The & operator is used to convert a function argument into a reference.
Code:
<!DOCTYPE html>
<html>
<body>
<?php
functionaddition(&$val) {
$val += 10;
}
$number =5;
addition($number);
echo $number;
?>
</body>
</html>
Output:
PHP Is a Loosely Typed Language
Depending on the variable’s value, PHP automatically assigns it a data form. You can do things like adding a string to an integer without making an error because the data types strictly aren't set. Kind declarations were introduced in PHP 7. This allows one to define the intended data type when declaring a method, and the strict declaration ensures that if the data type mismatches, a "Fatal Error" is thrown.
Without using strict, we try to submit both a number and a string to the function in the following example:
Example:
<?php
function add(int $s, int $t) {
return $s + $t;
}
echo add(5, "8 days");
// since strict is NOT enabled, "8 days" is changed to int(8), and it will return 13.
?>
Output:
PHP Functions - Returning Value
This means the PHP Function can be called by its name, and when executing the function, it will return some value.
Example:
<?php
function circle($r){
return 3.14*$r*$r;
}
echo "Area of circle is: ".circle(3);
?>
Output:
Setting Default Values for Passing Arguments
It is possible to specify a default argument value in the function. While calling the Function in PHP, it will take the default value if no arguments are passed.
Example:
<?php declare(strict_types=1); // strict requirement ?>
<!DOCTYPE html>
<html>
<body>
<?php
functionsetval(int $a = 5) {
echo "The value is : $a <br>";
}
setval(50);
setval();
setval(13);
setval(40);
?>
</body>
</html>
Output:
Dynamic Function Calls
In Dynamic Function Calls, it is possible to assign function names to variables as strings and then handle them as function names.
Code:
<html>
<head>
<title>Listing 6.5</title>
</head>
<body>
<?php
function say() {
print "hello<br>";
}
$function_holder = "Hello";
$function_holder();
?>
</body>
</html>
Output:
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Conclusion
In this article, we learned that a function in PHP is a section of code in a program that is written to perform a specific task. We discussed that they take data as a parameter, run a block of statements, perform operations, and then return the result. We discussed creating calling the function, functions with parameters, passing default values as arguments. We also learned about loosely-typed references.
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