PHP Operators

This section lists the different operators used in PHP.

Arithmetic Operators

Operator	Description	Example	Result
+	Addition	x=2 x+2	4
-	Subtraction	x=2 5-x	3
*	Multiplication	x=4 x*5	20
/	Division	15/5 5/2	3 2.5
%	Modulus (division remainder)	5%2 10%8 10%2	1 2 0
++	Increment	x=5 x++	x=6
--	Decrement	x=5 x--	x=4

Assignment Operators

Operator	Example	Is The Same As
=	x=y	x=y
+=	x+=y	x=x+y
-=	x-=y	x=x-y
*=	x*=y	x=x*y
/=	x/=y	x=x/y
.=	x.=y	x=x.y
%=	x%=y	x=x%y

Comparison Operators

Operator	Description	Example
==	is equal to	5==8 returns false
!=	is not equal	5!=8 returns true
<>	is not equal	5<>8 returns true
>	is greater than	5>8 returns false
<	is less than	5<8 returns true
>=	is greater than or equal to	5>=8 returns false
<=	is less than or equal to	5<=8 returns true

Logical Operators

Operator	Description	Example
&&	and	x=6 y=3 (x < 10 && y > 1) returns true
||	or	x=6 y=3 (x==5 || y==5) returns false
!	not	x=6 y=3 !(x==y) returns true

PHP String Constants

Constant	Description
CRYPT_SALT_LENGTH	Contains the length of the default encryption method for the system. For standard DES encryption, the length is 2
CRYPT_STD_DES	Set to 1 if the standard DES-based encryption with a 2 character salt is supported, 0 otherwise
CRYPT_EXT_DES	Set to 1 if the extended DES-based encryption with a 9 character salt is supported, 0 otherwise
CRYPT_MD5	Set to 1 if the MD5 encryption with a 12 character salt starting with $1$ is supported, 0 otherwise
CRYPT_BLOWFISH	Set to 1 if the Blowfish encryption with a 16 character salt starting with $2$ or $2a$ is supported, 0 otherwise0
HTML_SPECIALCHARS
HTML_ENTITIES
ENT_COMPAT
ENT_QUOTES
ENT_NOQUOTES
CHAR_MAX
LC_CTYPE
LC_NUMERIC
LC_TIME
LC_COLLATE
LC_MONETARY
LC_ALL
LC_MESSAGES
STR_PAD_LEFT
STR_PAD_RIGHT
STR_PAD_BOTH

PHP String Functions

PHP: indicates the earliest version of PHP that supports the function.

Function	Description	PHP
addcslashes()	Returns a string with backslashes in front of the specified characters	4
addslashes()	Returns a string with backslashes in front of predefined characters	3
bin2hex()	Converts a string of ASCII characters to hexadecimal values	3
chop()	Alias of rtrim()	3
chr()	Returns a character from a specified ASCII value	3
chunk_split()	Splits a string into a series of smaller parts	3
convert_cyr_string()	Converts a string from one Cyrillic character-set to another	3
convert_uudecode()	Decodes a uuencoded string	5
convert_uuencode()	Encodes a string using the uuencode algorithm	5
count_chars()	Returns how many times an ASCII character occurs within a string and returns the information	4
crc32()	Calculates a 32-bit CRC for a string	4
crypt()	One-way string encryption (hashing)	3
echo()	Outputs strings	3
explode()	Breaks a string into an array	3
fprintf()	Writes a formatted string to a specified output stream	5
get_html_translation_table()	Returns the translation table used by htmlspecialchars() and htmlentities()	4
hebrev()	Converts Hebrew text to visual text	3
hebrevc()	Converts Hebrew text to visual text and new lines (\n) into	3
html_entity_decode()	Converts HTML entities to characters	4
htmlentities()	Converts characters to HTML entities	3
htmlspecialchars_decode()	Converts some predefined HTML entities to characters	5
htmlspecialchars()	Converts some predefined characters to HTML entities	3
implode()	Returns a string from the elements of an array	3
join()	Alias of implode()	3
levenshtein()	Returns the Levenshtein distance between two strings	3
localeconv()	Returns locale numeric and monetary formatting information	4
ltrim()	Strips whitespace from the left side of a string	3
md5()	Calculates the MD5 hash of a string	3
md5_file()	Calculates the MD5 hash of a file	4
metaphone()	Calculates the metaphone key of a string	4
money_format()	Returns a string formatted as a currency string	4
nl_langinfo()	Returns specific local information	4
nl2br()	Inserts HTML line breaks in front of each newline in a string	3
number_format()	Formats a number with grouped thousands	3
ord()	Returns the ASCII value of the first character of a string	3
parse_str()	Parses a query string into variables	3
print()	Outputs a string	3
printf()	Outputs a formatted string	3
quoted_printable_decode()	Decodes a quoted-printable string	3
quotemeta()	Quotes meta characters	3
rtrim()	Strips whitespace from the right side of a string	3
setlocale()	Sets locale information	3
sha1()	Calculates the SHA-1 hash of a string	4
sha1_file()	Calculates the SHA-1 hash of a file	4
similar_text()	Calculates the similarity between two strings	3
soundex()	Calculates the soundex key of a string	3
sprintf()	Writes a formatted string to a variable	3
sscanf()	Parses input from a string according to a format	4
str_ireplace()	Replaces some characters in a string (case-insensitive)	5
str_pad()	Pads a string to a new length	4
str_repeat()	Repeats a string a specified number of times	4
str_replace()	Replaces some characters in a string (case-sensitive)	3
str_rot13()	Performs the ROT13 encoding on a string	4
str_shuffle()	Randomly shuffles all characters in a string	4
str_split()	Splits a string into an array	5
str_word_count()	Count the number of words in a string	4
strcasecmp()	Compares two strings (case-insensitive)	3
strchr()	Finds the first occurrence of a string inside another string (alias of strstr())	3
strcmp()	Compares two strings (case-sensitive)	3
strcoll()	Locale based string comparison	4
strcspn()	Returns the number of characters found in a string before any part of some specified characters are found	3
strip_tags()	Strips HTML and PHP tags from a string	3
stripcslashes()	Unquotes a string quoted with addcslashes()	4
stripslashes()	Unquotes a string quoted with addslashes()	3
stripos()	Returns the position of the first occurrence of a string inside another string (case-insensitive)	5
stristr()	Finds the first occurrence of a string inside another string (case-insensitive)	3
strlen()	Returns the length of a string	3
strnatcasecmp()	Compares two strings using a "natural order" algorithm (case-insensitive)	4
strnatcmp()	Compares two strings using a "natural order" algorithm (case-sensitive)	4
strncasecmp()	String comparison of the first n characters (case-insensitive)	4
strncmp()	String comparison of the first n characters (case-sensitive)	4
strpbrk()	Searches a string for any of a set of characters	5
strpos()	Returns the position of the first occurrence of a string inside another string (case-sensitive)	3
strrchr()	Finds the last occurrence of a string inside another string	3
strrev()	Reverses a string	3
strripos()	Finds the position of the last occurrence of a string inside another string (case-insensitive)	5
strrpos()	Finds the position of the last occurrence of a string inside another string (case-sensitive)	3
strspn()	Returns the number of characters found in a string that contains only characters from a specified charlist	3
strstr()	Finds the first occurrence of a string inside another string (case-sensitive)	3
strtok()	Splits a string into smaller strings	3
strtolower()	Converts a string to lowercase letters	3
strtoupper()	Converts a string to uppercase letters	3
strtr()	Translates certain characters in a string	3
substr()	Returns a part of a string	3
substr_compare()	Compares two strings from a specified start position (binary safe and optionally case-sensitive)	5
substr_count()	Counts the number of times a substring occurs in a string	4
substr_replace()	Replaces a part of a string with another string	4
trim()	Strips whitespace from both sides of a string	3
ucfirst()	Converts the first character of a string to uppercase	3
ucwords()	Converts the first character of each word in a string to uppercase	3
vfprintf()	Writes a formatted string to a specified output stream	5
vprintf()	Outputs a formatted string	4
vsprintf()	Writes a formatted string to a variable	4
wordwrap()	Wraps a string to a given number of characters	4

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strpos() function

The strpos() function is used to search for character within a string.

If a match is found, 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");
?>

The output of the code above will be:

6

strlen() function

The strlen() function is used to return the length of a string.

Let's find the length of a string:

<?php
echo strlen("Hello world!");
?>

The output of the code above will be:

12

The Concatenation Operator

There is only one string operator in PHP.

The concatenation operator (.)  is used to put two string values together.

To concatenate two string variables together, use the concatenation operator:

<?php
$txt1="Hello World!";
$txt2="What a nice day!";
echo $txt1 . " " . $txt2;
?>

The output of the code above will be:

Hello World! What a nice day!

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 (a space character), to separate the two strings.

PHP String Variables

A string variable is used to store and manipulate text.

String Variables in PHP

String variables are used for values that contains characters.

In this chapter we are going to look at the most common functions and operators used to manipulate strings in PHP.

After we create a string we can manipulate it. A string can be used directly in a function or it can be stored in a variable.

Below, the PHP script assigns the text "Hello World" to a string variable called $txt:

<?php
$txt="Hello World";
echo $txt;
?> 

The output of the code above will be:

Hello World

PHP : Naming Rules for Variables

• A variable name must start with a letter or an underscore "_"
• A variable name can only contain alpha-numeric characters and underscores (a-z, A-Z, 0-9, and _ )
• A variable name should not contain spaces. If a variable name is more than one word, it should be separated with an underscore ($my_string), or with capitalization ($myString)

PHP : a Loosely Typed Language

In PHP, a variable does not need to be declared before adding a value to it.

In the example above, you see that you do not have to tell PHP which data type the variable is.

PHP automatically converts the variable to the correct data type, depending on its value.

In a strongly typed programming language, you have to declare (define) the type and name of the variable before using it.

In PHP, the variable is declared automatically when you use it.

PHP Variables

A variable is used to store information.

Variables are used for storing a values, like text strings, numbers or arrays.

When a variable is declared, it can be used over and over again in your script.

All variables in PHP start with a $ sign symbol.

The correct way of declaring a variable in PHP:

$var_name = value;

New PHP programmers often forget the $ sign at the beginning of the variable. In that case it will not work.

Let's try creating a variable containing a string, and a variable containing a number:

<?php
$txt="Hello World!";
$x=16;
?> 

Comments in PHP

In PHP, we use // to make a single-line comment or /* and */ to make a large 
comment block.

<html>

<body>

<?php

//This is a comment

/*

This is a comment 
block

*/

?>

</body>

</html> 

PHP Syntax

PHP code is executed on the server, and the plain HTML result is sent 
to the browser.

Basic PHP Syntax

A PHP scripting block always starts with <?php and ends with ?>. 
A PHP scripting block can be placed anywhere in the document.

On servers with shorthand support enabled you can start a scripting block 
with <? and end with ?>.

For maximum compatibility, we recommend that you use the standard 
form (<?php) rather than the shorthand form.

<?php

?>

A PHP file normally contains HTML tags, just like an HTML file, 
and some PHP scripting code.

Below, we have an example of a simple PHP script which sends 
the text "Hello World" to the browser:

<html>

<body>

<?php

echo "Hello World";

?>

</body>

</html>

Each code line in PHP must end with a semicolon. The semicolon is a 
separator and is used to distinguish one set of instructions from another.

There are two basic statements to output text with PHP: echo and print. 
In the example above we have used the echo statement to output the 
text "Hello World".

Note: The file must have a .php extension. If the file has a .html extension, 
the PHP code will not be executed.