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PHP String Functions


PHP string functions

PHP has over 75 built-in String manipulation functions, supporting operations ranging from string repetition and reversal to comparison and search-and-replace. Some of these important functions are

Sr Function What it Does
1 empty() Tests if a string is empty
2 strlen() Calculates the number of characters in a string
3 strrev() Retrun reverse of a given string
4 str_repeat() Repeats a string no. of times you want
5 substr() Retrieves a section of a string
6 strcmp() Compares two strings
7 str_word_count() Calculates the number of words in a string
8 str_replace() Replaces parts of a string
9 trim() removes leading and trailing whitespaces from a string
10 strtolower() Converts in Lowercases a string
11 strtoupper() Converts in Uppercases a string
12 ucfirst() Converts in uppercase the first character of a string
13 ucwords() Converts in uppercases the first character of every word of a string
14 addslashes() Escapes special characters in a string with backslashes
15 stripslashes() Removes backslashes from a string
16 htmlentities() Encodes HTML within a string
17 htmlspecialchars() Encodes special HTML characters within a sting
18 nl2br() Replaces line breaks in a string with elements
19 html_entity_decode() Decodes HTML entities within a string
20 htmlspecialchars_decode() Decodes special HTML characters withing a string
21 strip_tags() Removes PHP and HTML code from a string
22 md5() The MD5 message-digest algorithm is a widely used for cryptography
23 str_split() str_split() function splits(break) a string into an array.

Here's example illustrating these operators in action


Eg ii ( strrev( ) )

<?php
	
$val="nitin";
	
if(strrev($val)==$val)
	
echo "Your name is palindrome";
	
else
	
echo "Your name is not palindrome";
  
?>

Output
Your name is palindrome

In the above example,
Declare variable $val hold value="nitin". Here we use strrev() Function to give reverse of a string.
We pass strrev() function inside If condition. if the reverse string is equal to declared string.
it will print "Your name is palindrome" otherwise "Your name is not palindrome"


Eg iii (str_repeat( ) )

<?php
    
$val="welcome ";
   
 echo str_repeat($val,3);
  
 ?>

Output
welcome welcome welcome

In the above example,
Declare variable $val with value="welcome".
use str_repeat( ) function with two argument. first argument declare name of variable, second argument we define number of times print the value.
The output is (welcome welcome welcome) because we pass 3 second argument.


Eg iv ( str_replace( ) )

<?php
  	
$str="welcome";
	
echo str_replace("e","@",$str);
  
?>

Output
w@lcom@

In the above example,
Declare variable $str with value="welcome".
use str_replace( ) function. It accepts three argument: the search term, the replacement term, and the string on which perform replacement.
we have Passed str_replace("e","@",$str) and the output is : W@lcom@ because "@" replaced by "e".


Eg v ( str_word_count( ) )

<?php
  
$str="hello  user how r you";
  
echo str_word_count($str);
  
?>

Output
5

In the above example,
Use str_word_count( ) function is used to count the number of word in a string.
declare variable $str value="hello user how are you".
pass this function inside echo so the output is :5 (count words separated by space)


Eg vi ( strcmp( ) )

<?php
$str="hello";	
$str1="HELLO";	
echo strcmp($str,$str1);  
?>
Output
1

In the above example,
declare two variable $str value=("hello")
$str1 with value=("HELLO")
Now compare two string using strcmp( ) function.
display the output i.e 1 because both variable doesn't contain same value(one is in lowercase while other in uppercase).


Eg vii(strlen( ))

<?php
    
if(isset($_GET['sub']))
	
{
		
if(empty($_GET['n']))
		
{
		
echo "<font color='red'>fill your name first</font>";
		
}
		
else
		
{
			
if(strlen($_GET['n'])<5)
			
{
			
echo "<font color='red'>name must be greater than 5</font>";
			
}
			
else
			
{
			
echo "welcome ".$_GET['n'];
			
}
		
}
	
}

?>

<form>

	Enter your name<input type="text" name="n"/>

	<input type="submit" name="sub" value="show my name"/>

</form>

Output
name must be greater than 5
Enter your name

Eg viii ( strpos( ) )

<?php
       
$str="welcome";
       
echo strpos($str,"l");
  
?>

Output
2

Eg ix ( nl2br( ) )

<?php
	
$str1="hello 
	
user
	
how 
	
are
	
you";
	
echo nl2br($str1);
  
?>
Output
hello
user
how
are
you

Eg x( substr( ) )

<?php
	
$str="welcome to the world of php";
	
echo substr($str,24,3);
 
?>

Output
php


In the above example,
substr( ) function is used to slice string into smaller section.
it accepts three argument: (given string ,the position at which start slicing , and the number of character return from the starting position ).
$str hold a string value="welcome to the world of php" now pass substr($str,24,3) function inside echo and the output will become: php


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