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Tuesday, April 29, 2008

String Manipulation Functions in PHP

In the previous post Properties of String in PHP, we were discussing about the different properties of strings in PHP. String manipulation as you know, is an important part of web programming. PHP being a web programming language thus provides good set of string manipulation functions. In this post we’re going to discuss some of those which arte frequently needed.

1. trim() function

Prototype: string trim (string str);

This function strips white spaces from the start and end of the string supplied returning the resulting string..

When we have to take user input via form, it’d be a good idea to “trim” the variables as extra white spaces sometimes creep in.

$name=trim($_GET['name'];

2. explode() function

Prototype: array explode (string separatorstring inputint limit);
The argument “limit” is optional.

This function splits the string “input” on a specified “separator” and returns the different split strings as an array. The optional parameter “limit” determines the maximum number of splitting you want.

$str="String Manipulation in PHP";
$arr=explode(" "$str);

Now $arr would be having the following values:

$arr[0]="String";
$arr[1]="Manipulation";
$arr[2]="in";
$arr[3]="PHP";

2. substr() function

Prototype: string substr (string strint startint length);
“length” is optional.

This function can help you take a sub string starting from the position “start” till the end (or the “length”, if specified) from the string “str”.


$str="She is here";
$s=substr($str1);
$s2=substr($str15);

$s will contain “he is here”.
$s2 will contain “he is”.

Note: Position of first character is 0.

4. strlen() function

Prototype: int strlen (string str);

It returns the length of the string “str”.

$str="PHP is Great";
$len=strlen($str);

$len = 12 here.

5. strcmp() function

Prototype: int strcmp (string str1string str2);

This function does a case-sensitive comparison of the two strings passed “str1” and “str2” and returns 0 if both are identical. It returns other negative and positive values in other cases depending on which string is greater in lexicographic order.

6. strpos() function

Prototype: int strpos (string haystackstring needleint offset);
“offset” is optional. “needle” is the string to be searched for in “haystack”.

It returns the position of the first occurrence of the string “needle” in “haystack” starting from the position “offset”, if specified.

$haystack="We are discussing string manipulation functions in PHP";
$needle="are";
$pos=strpos($haystack$needle);

$pos will contain 3.

Note: Position of first character is 0.

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