PHP
Strings
They are sequences of characters, like "PHP
supports string operations".
NOTE −
Built-in string functions is given in function reference PHP String
Functions
Following are valid examples of string
$string_1
= "This is a string in double quotes";
$string_2
= "This is a somewhat longer, singly quoted string";
$string_39
= "This string has thirty-nine characters";
$string_0
= ""; // a string with zero characters
Singly quoted strings are treated almost literally,
whereas doubly quoted strings replace variables with their values as well as
specially interpreting certain character sequences.
<?php
$variable = "name";
$literally = 'My $variable will not print!\\n';
print($literally);
print "<br
/>";
$literally = "My $variable will print!\\n";
print($literally);
?>
This will produce the following result −
My
$variable will not print!\n
My name
will print
There are no artificial limits on string length -
within the bounds of available memory, you ought to be able to make arbitrarily
long strings.
Strings that are delimited by double quotes (as in
"this") are preprocessed in both the
following two ways by PHP −
·
Certain character sequences beginning
with backslash (\) are replaced with special characters
·
Variable names (starting with $) are
replaced with string representations of their values.
The escape-sequence replacements are −
String
Concatenation Operator
To concatenate two string variables together, use
the dot (.) operator −
<?php
$string1="Hello
World";
$string2="1234";
echo $string1 . " " .
$string2;
?>
This will produce the following result −
Hello
World 1234
If we look at the code above you see that we used
the concatenation operator two times. This is because we had to insert a third
string.
Between the two string variables we added a string
with a single character, an empty space, to separate the two variables.
Using the strlen()
function
The strlen() function is used to find the length of a string.
Let's find the length of our string "Hello
world!":
<?php
echo strlen("Hello world!");
?>
This will produce the following result −
12
The length of a string is often used in loops or
other functions, when it is important to know when the string ends. (i.e. in a loop, we would want to stop the loop after the
last character in the string)
Using the strpos()
function
The strpos() function is used to search for a string or character
within a string.
If a match is found in the string, this function
will return the position of the first match. If no match is found, it will
return FALSE.
Let's see if we can find the string
"world" in our string −
<?php
echo strpos("Hello world!","world");
?>
This will produce the following result −
6
As you see the position of the string
"world" in our string is position 6. The reason that it is 6, and not
7, is that the first position in the string is 0, and not 1.