PHP Functions
- A function is a block of statements that can be used repeatedly in a program.
- A function will not execute immediately when a page loads.
- A function will be executed by a call to the function.
- Are named section of a program
- Are used to perform a specific task
- Split program into modules
- Are used to enable the developer to reuse the same piece of code
- Can be easily modified in a program instead of going through entire code to make changes.
- Function names are NOT case-sensitive.
- We can set PHP Default Argument Value.
- Statements are grouped into a single unit to perform a specific task
- Enhance the logical flow in a program by dividing complicated code sequences into smaller modules
- Enable to write a piece of code and assign a name to it
- Include parameters that are:
- Variables
- Specified within the parenthesis after the name of a function
- Used to add more functionality
- Executed or invoked anywhere in the program using the assigned name
TYPES OF FUNCTIONS
There are 2 types of functions
- Built-in or pre-defined functions
- Custom or user-defined functions
The real power of PHP comes from its functions; it has more than 1000 built-in functions.
User-defined or custom Functions
- Function can be defined or created
- Function definition contains the code to be executed
- The return expression statement within the body of the function is used to return a value from a function.
- Note: A function name can start with a letter or underscore (not a number).
- Tip: Give the function a name that reflects what the function does!
PARAMETERS VS ARGUMENTS
Built-in PHP Functions
- Provides different built-in functions to be included in the PHP script
- Built-in functions are grouped into following categories:
- Mathematical functions
- String functions
- Date and time functions
- Error handling functions
- Database functions
- Array functions
- Mail functions
STRING FUNCTIONS
OPERATE ON CHARACTER TYPE OF DATA.
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Untitled Document</title>
</head>
<body>
<?php
// $str1 = "nasir"; // 78
// $str2 = "nasir"; // 110
//
// if(strcmp($str1,$str2) == 0)
// {
// echo "Strings Are Same";
// }
// else
// {
// echo "Strings Are Not Same";
// }
// echo strcmp($str1, $str2);
$str = "my name is adil ansari";
// echo strrchr($str,"a");
echo stristr($str, "a");
// $name = "adil";
// echo strrev($name);
// echo strlen($name);
// echo strtolower($name);
// echo strtoupper($name);
// echo bin2hex("A");
// for($i = 97; $i <= 122; $i++)
// {
// echo chr($i) . "<br>";
// }
?>
</body>
</html>MATHEMATICAL FUNCTIONS
OPERATE ON NUMERICAL DATA.
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Untitled Document</title>
</head>
<body>
<?php
// $num1 = 10;
// $num2 = 5;
// $num3 = 45;
// $num4 = 2;
// echo rand(1,10000000);
// echo rand()*50;
// $a = 5.9; // 5 ----- 5.9 ----------- 6
// echo floor($a);
// echo ceil($a);
// echo round($a);
// echo pow(2, 3); // 2 X 2 X 2
// echo sqrt(12);
// echo min(22,33,44,55);
// echo max(22,33,44,55);
// $a = -5;
// echo abs($a);
?>
</body>
</html>DATE FUNCTION PHP
Some of the formats that can be used are as follows:
- d — day of the month
- D — textual representation of the day
- l — full name of day
- j — day of the month without leading zeros (1 to 31)
- m — numeric representation of the month
- M — textual representation of the month
- y — a two digit representation of the year
- Y — a four digit representation of the year
- a — Lowercase am or pm
- A — Uppercase am or pm
- h — 12 hour format of an hour
- H — 24 hour format of an hour
- i — minutes with leading zero
- s — seconds with leading zeros
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Untitled Document</title>
</head>
<body>
<?php
date_default_timezone_set("Asia/Karachi");
// echo date("d");
// echo date("D");
// echo date("l");
// echo date("d");
// echo date("m");
// echo date("M");
// echo date("y");
// echo date("Y");
// echo date("d-m-y");
// echo date("l/M/Y");
// echo date("h");
// echo date("a");
// echo date("A");
// echo date("H");
// echo date("i");
// echo date("s");
echo date("h:i:s A");
?>
</body>
</html>Passing Arguments to Functions
- PHP supports passing of arguments to a function
- The three different ways of passing arguments to a function are as follows:
- Passing arguments by value
- Passing arguments by reference
- Setting default values for arguments
- The function definition determines the method of passing arguments to the function
Pass by value
- Passes an argument by value.
- In this, you are sending a copy of the data.
- Changes does not affect the actual value.
Pass by reference
- Passes an argument by reference.
- In this, you are passing the memory address of the data that is stored.
- Changes to the value effect the original data.
Source Code
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Untitled Document</title>
</head>
<body>
<?php
// function Show()
// {
// echo "Statement No 1 <br>";
// echo "Statement No 2 <br>";
// echo "Statement No 3 <br>";
// }
//
// show();
//function Add($num1, $num2)
//{
// $add = $num1 + $num2;
// echo $add;
//}
// Add(10, 20);
// function ShowName($name = "Anonymous")
// {
// echo "Your Name is $name <br>";
// }
//
// ShowName();
// function ShowAge($age = 18)
// {
// echo "Your Age is $age <br>";
// }
//
// ShowAge();
function Subtract($num1, $num2)
{
$sub = $num1 - $num2;
return $sub;
}
$a = Subtract(20,5);
$b = 10 + $a;
echo $b;
?>
</body>
</html>Download Notes Of This Blog From the link given below
https://www.mediafire.com/file/msv6z1ecciqhql4/FUNCTIONS+PHP.pptx/file
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