PHP
Programmer should know the following string functions in PHP.
Note : In the
below mentioned functions the parameters marked in < and > tags are
mandatory and
the
parameters marked in [< and >] are optional
substr()
This
function returns the part of the string as an output.
Syntax
:
substr(<string>,<start>,[<length>]);
Explanation
:
String
: It is mandatory parameter. The string from which the part is to be extracted
is mentioned
here.
Start :
The start in the string from which the characters are to be extracted
· Positive number - Start at a specified position in the
string
· Negative number - Start at a specified position from the
end of the string
· 0 - Start at the first character in string
Length
: It is an optional parameter. It specifies the length of the string which is
to be extracted.
· Positive number - The length to be returned from the start
parameter
· Negative number - The length to be returned from the end
of the string
Example
1:
<?php
echo substr("Hello world",6); ?> //Returns world
Example
2 :
<?php
echo substr("Hello world",6,4); ?> // Returns worl
Example
3 :
<?php
echo substr("Hello world", -1); ?> // Returns d
Example
4:
<?php
echo substr("Hello world", -3, -1); ?> // Returns rl
strlen()
This
function returns the length of the string
Syntax
:
strlen(<string>);
Explanation:
String
: It is mandatory field. The string whose length is to be found out is
mentioned here.
Example
1:
<?php
echo strlen("Hello world"); ?> // Returns 11
trim()
This
function removes the whitespaces from both start and the end of the string.
Syntax
:
trim(<string>);
Explanation
:
String
: It is mandatory field. The string of which the whitespaces are to be removed
is passed as
parameter.
Example
1:
<?php
echo trim( " Hello World "); ?> // returns Hello World. If you go
view source then you
can see
that there are no whitespaces.
ltrim()
This
function removes the whitespaces from the left part of the string.
Syntax
:
ltrim(<string>);
Explanation
:
String
: It is mandatory field. The string of which the whitespaces are to be removed
from left side is
passed
as parameter.
Example
1:
<?php
echo ltrim( " Hello World "); ?> // returns Hello World. If you go
view source then you
can see
that there are no whitespaces on left side but there are spaces on right side.
rtrim()
This
function removes the whitespaces from the right part of the string.
Syntax
:
rtrim(<string>);
Explanation
:
String
: It is mandatory field. The string of which the whitespaces are to be removed
from right side
is
passed as parameter.
Example
1:
<?php
echo rtrim( " Hello World "); ?> // returns Hello World. If you go
view source then you
can see
that there are no whitespaces on right side but there are spaces on left side
strtolower()
This
function converts the string to lower case
Syntax
:
strtolower(<string>);
Explanation
:
String
: It is mandatory field. The string which is to be converted to lower case is
passed here.
Example
1:
<?php
echo strtolower("HELLO WORLD"); ?> // Returns hello world
strtoupper()
This
function converts the string to upper case
Syntax
:
strtoupper(<string>);
Explanation
:
String
: It is mandatory field. The string which is to be converted to upper case is
passed here.
Example
1:
<?php
echo strtoupper("hello world"); ?> // Returns HELLO WORLD
str_replace()
The
str_replace() function replaces some characters with some other characters in a
string.
This
function works by the following rules:
· If the string to be searched is an array, it returns an
array
· If the string to be searched is an array, find and replace
is performed with every array
element
· If both find and replace are arrays, and replace has fewer
elements than find, an empty
string
will be used as replace
· If find is an array and replace is a string, the replace
string will be used for every find value
Syntax
:
str_replace(<search>,<replace>,<string/array>,[<count>]);
Explanation
:
Search
: It is mandatory . The string or value to be searched comes here.
Replace
: It is mandatory. The string or value to be replaced comes here.
String/Array
: It is mandatory. The string or array in which the value is to be found out
comes here.
Count :
It is optional. It counts the number of replacements to be done.
Example
1:
<?php
echo str_replace("world","Peter","Hello world");
?>// Returns Hello Peter
Example
2:
<?php
$arr =
array("blue","red","green","yellow");
print_r(str_replace("red","pink",$arr,$i));
echo
"Replacements: $i";
?>
/*
Output
:
Array
(
[0]
=> blue
[1]
=> pink
[2]
=> green
[3]
=> yellow
)
Replacements:
1
*/
Example
3:
<?php
$phrase
= "You should eat fruits, vegetables, and fiber every day.";
$healthy
= array("fruits", "vegetables", "fiber");
$yummy
= array("pizza", "beer", "ice cream");
$newphrase
= str_replace($healthy, $yummy, $phrase);
?>
/*
Output
:
You
should eat pizza, beer, and ice cream every day
*/
strcmp()
The
strcmp() function compares two strings.
This
function returns:
· 0 - if the two strings are equal
· <0 - if string1 is less than string2
· >0 - if string1 is greater than string2
Syntax
:
strcmp(<string1>,<string2>);
Explanation
:
String1
: It is mandatory. The first string comes here.
String
2 : It is mandatory. The Second string comes here.
Example
1:
<?php
echo strcmp("Hello world!","Hello world!"); ?> //Returns
0
Note: The
strcmp() function is binary safe and case-sensitive. For case insensitive
comparison you
can use
strcasecmp(<string1>,<string2>); function. It is similar to
strcmp() function.
explode()
This
function breaks the string into array on the basis of delimiter passed.
Syntax:
explode(<delimeter>,<string>,[<limit>]);
Explanation:
Delimeter:
It is mandatory field. It specifies where to break the string.
String:
It is mandatory. It specifies the string to split.
Limit :
It is optional. It specifies the maximum number of array elements to return.
Example
1:
<?php
$str =
"Hello world. It's a beautiful day.";
print_r
(explode(" ",$str));
?>
/*
Output :
Array
(
[0]
=> Hello
[1]
=> world.
[2]
=> It's
[3]
=> a
[4]
=> beautiful
[5]
=> day.
)
*/
implode()
This
function join array elements with a string on the basis of delimiter passed.
Syntax:
implode(<delim>,<array>);
Explanation:
Delimiter:
It is mandatory field. It specifies what to put between the array elements.
Default is "" (an
empty
string).
Array:
It is mandatory field. It specifies the array to join to a string.
Example
1:
<?php
$arr =
array('Hello','World!','Beautiful','Day!');
echo
implode(" ",$arr);
?>
/*
Output:
Hello
World! Beautiful Day!
*/
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