Substr Function in PHP

Introduction

In this article I will explain the string Substr() function in PHP. This function returns parts of the string starting at a specified position.

Syntax

substr('str_name', start_pos);

 

Parameter	Description
string_name	Pass the string name or string
start_pos	Refers to the position of the string to be cut

In the parameter the input string must be one character or longer and the "substr()" function returns the portion of the string specified by the start position and length parameter.   

Using a Negative Start

If the starting position is non-negative then the returned string will start at the start the position in the string and the index counts from zero. Such as in the string Ram, the character R is at index zero and space is at index three.

Example

<?php
$a = "MCN Sulotion";  
$b = "Ram Kumar";  
$c = "Shyam Kumar";
echo substr("$a",-1)."<br>";
echo substr("$b",-2)."<br>";
echo substr("$c",-3,1)."<br>";
?>

Output

Using a Negative Length

If the specified length is positive then the string returned will contain at most length characters beginning from start (depending on the string length). If the length is zero, then an empty string will be returned zero or false.

Example

<?php
$a = "MCN Sulotion";  
$b = "Ram Kumar";  
$c = "Shyam Kumar";
$d = "Sharad Kumar";
echo substr("$a",0, -1)."<br>";
echo substr("$b",2, -1)."<br>";
echo substr("$c",4, -4)."<br>";
echo substr("$d", -3, -1)."<br>";
?>

Output

Basic substr() Usage

Example

<?php 
// Accessing single characters in a string
// can also be done using "square brackets"
$string = 'ABCDEF';
echo $string[0]."<br>";               
echo $string[3]."<br>";              
echo $string[strlen($string)-1];
?>

Output

Casting Behavior substr()

<?php
class MCN {
    public function __toString() {
        return "PHP";
    }
}
echo "1] ".var_export(substr("pear", 0, 2), true).PHP_EOL."<br>";
echo "2] ".var_export(substr(54321, 0, 2), true).PHP_EOL."<br>";
echo "3] ".var_export(substr(new MCN(), 0, 2), true).PHP_EOL."<br>";
echo "4] ".var_export(substr(true, 0, 1), true).PHP_EOL."<br>";
echo "5] ".var_export(substr(false, 0, 1), true).PHP_EOL."<br>";
echo "6] ".var_export(substr("", 0, 1), true).PHP_EOL."<br>";
echo "7] ".var_export(substr(1.2e3, 0, 4), true).PHP_EOL."<br>";
?>

Output