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

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Here’s example illustrating these operators in action

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Eg i ( empty( ) )

<?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>

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<?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.

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Eg ii ( strrev( ) )

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

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<?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”

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Eg iii (str_repeat( ) )

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

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<?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.

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Eg iv ( str_replace( ) )

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

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<?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”.

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Eg v ( str_word_count( ) )

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

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<?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)

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Eg vi ( strcmp( ) )

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

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<?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).

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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>

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<?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

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Eg viii ( strpos( ) )

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

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

Output
2

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Eg ix ( nl2br( ) )

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

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

Output
hello
user
how
are
you

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Eg x( substr( ) )

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

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<?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