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

Function	What it Does
empty()	Tests if a string is empty
strlen()	Calculates the number of characters in a string
strrev()	Retrun reverse of a given string
str_repeat()	Repeats a string no. of times you want
substr()	Retrieves a section of a string
strcmp()	Compares two strings
str_word_count()	Calculates the number of words in a string
str_replace()	Replaces parts of a string
trim()	removes leading and trailing whitespaces from a string
strtolower()	Converts in Lowercases a string
strtoupper()	Converts in Uppercases a string
ucfirst()	Converts in uppercase the first character of a string
ucwords()	Converts in uppercases the first character of every word of a string
addslashes()	Escapes special characters in a string with backslashes
stripslashes()	Removes backslashes from a string
htmlentities()	Encodes HTML within a string
htmlspecialchars()	Encodes special HTML characters within a sting
nl2br()	Replaces line breaks in a string with  elements
html_entity_decode()	Decodes HTML entities within a string
htmlspecialchars_decode()	Decodes special HTML characters withing a string
strip_tags()	Removes PHP and HTML code from a string

Here’s example illustrating these operators in action

Eg i (use of empty( ) function)

<?php
 if(isset($_GET['sub']))
 {
 if(empty($_GET['n']))
  {
  echo "fill your name first";
  }
  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 :  welcome Rexx
     Enter your name
  

In the above example.
create a textbox and a submit button inside the form.
Pass value inside the textbox and click on button.then the value goes to PHP script page. $_GET is used to accept the value . empty() function is used to check the value which is entered by user.
If type something inside text box, it show a message welcome otherwise if value inside textbox in null (if statement execute) and show a message fill your name.

Eg ii (Use of strrev( ) function)

 <?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 (Use of str_repeat( ) function)

 <?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 (Use of str_replace( ) function)

 <?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 (Use of str_word_count( ) function)

  <?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 (Use of strcmp( ) function)

<?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(Use of strlen( ) function)

  <?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 (Use of strpos( ) function)

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

   Output : 2

Eg ix (Use of nl2br( ) function)

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

   Output : hello
           user
           how
           r
           you

In the above example
variable $str1 hold value=”hello
user
how
r
you”
nl2br() function replace newline character and output will become :”hello

user

how 

r

you”

Eg x (Use of substr( ) function)

  <?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