String variable in php

Instruction By:

Dr. Bou
eun Chhun 1

Content:

1. String Variable
2. Concatenate Operators
3. String with Single and Double
Quote
4. String with heredoc
5. The PHP strlen() function
6. The PHP strpos() function
7. The str_replace function
8. The strtoupper() function
9. The ucfirst() function
10. The trim() function 2
11. The strtolower() function

String Variable
 String variables are used for values that
contain characters.
 After we have created a string variable we
can manipulate it.
 A string can be used directly in a function
or it can be stored in a variable.
 Here is PHP script with string value
<?php
$str=‚This is String in PHP.‛;
echo $str;
?>
 Output of the above script are:
This is string in PHP 3

The PHP Concatenation Operator

 There is only one string operator in PHP.
 The concatenation operator (.) is used to
join two string values together.
 Below is the example of string
concatenation
<?php
$txt1="Hello world!";
$txt2="What a nice day!";
echo $txt1 . " " . $txt2;
?>
 The result of the above
Hello world What a nice day!
4

String with Single and Double
quote
 There are two way when you can specify a string in
php single quote and double quote.
 Single quoted strings are treated almost
literally.
 double quoted strings replace variables with their
values as well as specially interpreting certain
character sequences.
 Here is an example
<?php
$variable=‚name‛;
$literally=‘My $variable will not print
n’;
print($literally);
$literally=‚My $variable will print n‛;
5
print($literally);

 The result of the above code will be
My $variable will not print!n
My name will print
 String with double quote will process in both two way:
1. Certain character sequences beginning with backslash
() are replaced with special characters
2. Variable names (starting with $) are replaced with string
representations of their values.
 The escape-sequence replacements are:
n is replaced by the newline character
r is replaced by the carriage-return character
t is replaced by the tab character
$ is replaced by the dollar sign itself ($)
" is replaced by a single double-quote (")
is replaced by a single backslash () 6

String with Heredoc
 You can assign multiple lines to a single string
variable using heredoc .
 See the example below

<?php
echo <<<END
This uses the "here document" syntax to
output
multiple lines with variable
interpolation. Note
that the here document terminator must
appear on a
line with just a semicolon. no extra
whitespace! 7
<br />

 In code above after heredoc must be follow by
some identifier for example END and must be
end with the same identifier as the start one
with semiconlon sign
 Even though using heredoc is difficult and can
Couse some problem.
 Note that the closing sequence END; must occur
on a line by itself and cannot be indented.

8

The PHP strlen() Function

 Strlen() function used to return the length of
the string
example:
<?php
$str=‚Welcome back to PHP‛;
echo strlen($str);
?>
 Result will be
19
 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 9
the loop after the last character in the string).

The strops() Function

 Strpos() function is used to return the search
of character with in the string.
 If match is found, function will return the
position of the first character of the match
word.
example:
<?php
echo strpos(‛Welcome back to
PHP‛,‛PHP‛);
?>
 The result of the above script is follow
16
 The resean is that it return only the first
10
character of the whole word .

The str_replace function

 The str_replace function is use to search and
replace the search result with the new word.
 If no word match it will return the original
word.
example
<?php
$str=‚Welcome back to PHP.‛;
echo str_replace(‚PHP‛,‛PHP
Function‛,$str);
?>
 This will search for the word PHP and replace
with the word PHP Function.
 The result is: 11
Welcome back to PHP Function.

The strtoupper() Function

 The strtoupper() function is used to convert all
lowercase of the string word or sentence to
uppercase.
example
<?php
$str=‚start your first php with
w3school.‛;
echo strtoupper($str);
?>
 Here is the result
START YOUR FIRST PHP WITH
W3SCHOOL.
12

The strtolower() Function

 The strtolower() function is used to convert all
uppercase string to lowercase.
example
<?php
$str=‚START YOUR FIRST PHP WITH
W3SCHOOL.‛;
echo strtolower($str);
?>
 Here is the result
start your first php with w3school.

13

The ucfirst() function

 Ucfirst() function used to capital the first letter of
the first word in the whole string.
example
<?php
$str=‚using ucfirst() function.‛;
echo($str);
?>
 The result is
Using ucfirst() function.

14

The trim() function
 Trim() function strip a string of white space in
front and at the end of the whole string.
example
<?php
$str=‚ Welcome! ‛;
echo($str);
?>
 The above will result as below
Welcome!

15

Referent:

1. http://www.w3schools.com/php/php_string.asp
2. http://www.tutorialspoint.com/php/php_variable_types.htm

16

String variable in php

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