What is string in php?

String variables are used for values that contain characters. A string can be used directly in a function or it can be stored in a variable. String value are enclosed within single or double quotes marks.

Example.

<?php
$str = "Hello";
$ss = 'hi';

echo $str;
echo $ss;
?>

Output :-

Hello
hi

Difference between single ' ' quotation and double " " quotation. :-

singly quoted strings are treated almost literally, whereas doubly quoted string replace variable with their values as well as specially interpreting certain character sequence.

<?php
$var = "mahtab";
$str = 'my name is $var';
print ($str);
$ss = "my name is $var";
print($ss);
?>

Output :-
my name is $var
my name is mahtab

Concatenation operator :-

There is only one string operator in php. The concatenation operator (.) is used to join two string values together.

<?php
$str1 = "my name is ";
$str2 = "mahtab";
echo $str1. " " .$str2;
?>

Output :-

my name is mahtab

Example :-

<?php
$x = 5;
$y = star;
$add = $x.$y;
?>
Output :- 5star

strlen() function :-

It return the length of the string in characters.

<?php
$str = "mahtab";
echo $str;
$len = strlen($str);
echo $len;
echo strlen("hello");
?>
6 5

strops() function :-

The strops( ) function is used to search for a character or specific text within a string. If a match is found, it will return the character position of the first match. If no match is found it will return false.

<?php
echo strops("hello mahtab", "mahtab");
?>
Output :- 6

Comparing string :-

There are many ways in which two strings can be compared for equality.

strcmp()

strcasecmp( )

strspn( )

strcspn( )

The strcmp( ) function performs a binary-safe case-sensitive comparison of two string.

int strcmp(String str1, String str2) :- it will return one of the three possible values.
0 :- if str1 and str2 are equal.
-1 :- if str1 is less than str2.
1 :- if str1 is greater than str2.

<?php
$p1 = "password"; $p2 = "password2";
if(strcmp($p1, $p2) != 0)
{
echo "password don't match";
}
else
{
echo "password match";
}
?>

Case insensitivity :-

The strcasecmp( ) function operates exactly like strcmp( ), except that is comparison is case insensitive. Int strcasecmp(String s1, String s2)

<?php
$pwd1 = "mahtab"; $pwd2 = "MAHTAB";
if(! strcasecmp($pwd1, $pwd2) )
{
echo "password don't match";
}
else
{
echo "password match";
}
?>

Similiarity between Two Strings :-

The strspn( ) function returns the length of the first segment in a string containing characters also found in another strings.

<?php
$pwd = "12345678";
If(strspn ($pwd, "12345") == strlen($pwd))
Echo "passward doesn't match";
?>

String Functions :-

trim() :-

trim function remove white space from the the beginning and end of a string.

Syntax :-

trim(string,charlist)
here string is the user defined string.
charlist is the optional.
Specifies which characters to remove from the string. If omitted, all of the following characters are removed:
"\0" - NULL

"\t" - tab

"\n" - new line

"\x0B" - vertical tab

"\r" - carriage return

" " - ordinary white space

<?php
$str = " itech tuto ";
echo "Without trim: " . $str;
echo "<br>";
echo "With trim: " . trim($str);
?>

<?php
$str = "\n\n\nHello itechtuto!\n\n\n";
echo "Without trim: " . $str;
echo "<br>";
echo "With trim: " . trim($str);
?>

Output :-

Without trim: Hello World!
With trim: Hello World!

Other Function

ltrim() - Removes whitespace or other predefined characters from the beginning of a string
rtrim() - Removes whitespace or other predefined characters from the end of a string

Count The Number of Words in a String

The PHP str_word_count() function counts the number of words in a string:

<?php
echo str_word_count("Hello itechtuto");
?>

Output :-

2

Reverse a String

in PHP, strrev() function reverses a string:

<?php
echo strrev("Hello itechtuto");
?>

Output :-

otuthceti olleh

Replace Text Within a String

str_replace() function replaces some characters with some other characters in a string.

<?php
echo str_replace("gmaxlifesciences", "itechtuto", "Hello gmaxlifesciences!");
?>

Output :-

Hello itechtuto

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