Xtreme Coder

PHP string functions are used to manipulate string data. The most common string functions include the following :-


addcslashes — >Quote string with slashes in a C style
addslashes — >Quote string with slashes
bin2hex — >Convert binary data into hexadecimal representation
chop — >Alias of rtrim
chr — >Return a specific character
chunk_split — >Split a string into smaller chunks
convert_cyr_string — >Convert from one Cyrillic character set to another
convert_uudecode — >Decode a uuencoded string
convert_uuencode — >Uuencode a string
count_chars — >Return information about characters used in a string
crc32 — >Calculates the crc32 polynomial of a string
crypt — >One-way string hashing
echo — >Output one or more strings
explode — >Split a string by string
fprintf — >Write a formatted string to a stream
get_html_translation_table — >Returns the translation table used by htmlspecialchars and htmlentities
hebrev — >Convert logical Hebrew text to visual text
hebrevc — >Convert logical Hebrew text to visual text with newline conversion
html_entity_decode — >Convert all HTML entities to their applicable characters
htmlentities — >Convert all applicable characters to HTML entities
htmlspecialchars_decode — >Convert special HTML entities back to characters
htmlspecialchars — >Convert special characters to HTML entities
implode — >Join array elements with a string
join — >Alias of implode
lcfirst — >Make a string's first character lowercase
levenshtein — >Calculate Levenshtein distance between two strings
localeconv — >Get numeric formatting information
ltrim — >Strip whitespace (or other characters) from the beginning of a string
md5_file — >Calculates the md5 hash of a given file
md5 — >Calculate the md5 hash of a string
metaphone — >Calculate the metaphone key of a string
money_format — >Formats a number as a currency string
nl_langinfo — >Query language and locale information
nl2br — >Inserts HTML line breaks before all newlines in a string
number_format — >Format a number with grouped thousands
ord — >Return ASCII value of character
parse_str — >Parses the string into variables
print — >Output a string
printf — >Output a formatted string
quoted_printable_decode — >Convert a quoted-printable string to an 8 bit string
quoted_printable_encode — >Convert a 8 bit string to a quoted-printable string
quotemeta — >Quote meta characters
rtrim — >Strip whitespace (or other characters) from the end of a string
setlocale — >Set locale information
sha1_file — >Calculate the sha1 hash of a file
sha1 — >Calculate the sha1 hash of a string
similar_text — >Calculate the similarity between two strings
soundex — >Calculate the soundex key of a string
sprintf — >Return a formatted string
sscanf — >Parses input from a string according to a format
str_getcsv — >Parse a CSV string into an array
str_ireplace — >Case-insensitive version of str_replace.
str_pad — >Pad a string to a certain length with another string
str_repeat — >Repeat a string
str_replace — >Replace all occurrences of the search string with the replacement string
str_rot13 — >Perform the rot13 transform on a string
str_shuffle — >Randomly shuffles a string
str_split — >Convert a string to an array
str_word_count — >Return information about words used in a string
strcasecmp — >Binary safe case-insensitive string comparison
strchr — >Alias of strstr
strcmp — >Binary safe string comparison
strcoll — >Locale based string comparison
strcspn — >Find length of initial segment not matching mask
strip_tags — >Strip HTML and PHP tags from a string
stripcslashes — >Un-quote string quoted with addcslashes
stripos — >Find position of first occurrence of a case-insensitive string
stripslashes — >Un-quotes a quoted string
stristr — >Case-insensitive strstr
strlen — >Get string length
strnatcasecmp — >Case insensitive string comparisons using a "natural order" algorithm
strnatcmp — >String comparisons using a "natural order" algorithm
strncasecmp — >Binary safe case-insensitive string comparison of the first n characters
strncmp — >Binary safe string comparison of the first n characters
strpbrk — >Search a string for any of a set of characters
strpos — >Find position of first occurrence of a string
strrchr — >Find the last occurrence of a character in a string
strrev — >Reverse a string
strripos — >Find position of last occurrence of a case-insensitive string in a string
strrpos — >Find position of last occurrence of a char in a string
strspn — >Finds the length of the first segment of a string consisting entirely of characters contained within a given mask.
strstr — >Find first occurrence of a string
strtok — >Tokenize string
strtolower — >Make a string lowercase
strtoupper — >Make a string uppercase
strtr — >Translate certain characters
substr_compare — >Binary safe comparison of two strings from an offset, up to length characters
substr_count — >Count the number of substring occurrences
substr_replace — >Replace text within a portion of a string
substr — >Return part of a string
trim — >Strip whitespace (or other characters) from the beginning and end of a string
ucfirst — >Make a string's first character uppercase
ucwords — >Uppercase the first character of each word in a string
vfprintf — >Write a formatted string to a stream
vprintf — >Output a formatted string
vsprintf — >Return a formatted string
wordwrap — >Wraps a string to a given number of characters

Here we give an example of the PHP code that will read data out of a MySQL database and present it in a nice tabular format in HTML.
Assuming we have the following MySQL table:
Table Employee

Name	Salary
Lisa	40000
Alice	45000
Janine	60000

The PHP code needed is as follows (assuming the MySQL Server sits in localhost and has a userid = 'cat' and a password of 'dog', the database name is 'myinfo') :

$link = @mysql_pconnect("localhost","cat","dog") or exit(); mysql_select_db("myinfo") or exit(); print "<p>Employee Information"; print "<p><table border=1><tr><td>Employee Name</td><td>Salary Amount</td></tr>"; $result = mysql_query("select name, salary from Employee"); while ($row=mysql_fetch_row($result)) {   print "<tr><td>" . $row[0] . "</td><td>" . $row[1] . "</td></tr>"; } print "</table>";

Output is

Employee Information Employee Name Salary Amount Lisa 40000 Alice 45000 Janine 60000

Below is a quick explanation of the code:

$link = @mysql_pconnect("localhost","cat","dog") or exit(); mysql_select_db("myinfo") or exit();

These two lines tell PHP how to connect to the MySQL server.

$result = mysql_query("select name, salary from Employee");

This specifies up the query to be executed.

while ($row=mysql_fetch_row($result)) {   print "<tr><td>" . $row[0] . "</td><td>" . $row[1] . "</td></tr>"; }

$row[0] denotes the first column of the query result, namely the "name" field, and $row[1] denotes the second column of the query result, namely the "salary" field. The . in the print statement is the concatenation operator, and acts to combine the string before and string after together. The print statement continuess until all 3 rows have been fetched.

Previous Page->PHP-Redirect || Next Page->Tutorial-string-functions

If you have moved your pages, you can use PHP to perform a redirect to your new page.
The search engine friendly way of redirecting is the 301 redirect. In PHP, this is implemented as follows:

<? Header("HTTP/1.1 301 Moved Permanently"); Header("Location:http://www.new-site.com"); ?>

Make sure the above code is included before any HTML is produced. Otherwise, the redirect will not work.
A 301 redirect directs the search engine spiders to the new page, and ensures that all link juices to your old page are all passed to the new page.
Please note that if you do not include the first Header line above, the redirect still works. But, instead of a 301 redirect, now it becomes a 302 (temporary) redirect. 302 redirects are not search engine friendly, as it has become a common spam technique. So, if you want to ensure your search engine ranking is not affected by moving your file elsewhere or changing your file name, make sure you set up a 301 redirect.

Previous Page->PHP-Cookies || Next Page->PHP-mysql

If you have a website, you may wish to set a cookie on the client computer so that your site will remember that user when she returns. PHP provides ways to create, retrieve, and delete cookies.
Create cookies
Cookies are set using the setcookie() function. The syntax is as follows:
Setcookie (name, value, expire, path, domain, secure)
name = name of the cookie.
value = value of the cookie.
expire = time when this cookie will expire. Unix time is used here.
path = the path on the server on which the cookie is available.
domain = the domain that the cookie is available.
secure = TRUE means the cookie should be trasmitted over a secure connection (https), FALSE otherwise. FALSE is the default.
All arguments except name are optional. Unix time is the number of seconds that have elapsed since January 1, 1970.
You must make sure that the setcookie() function is called before any HTML output is printed.
Let's take a look at a couple of examples:

<?php   setcookie('cookie1','lisa'); ?>

This sets up a cookie with name = "cookie1" and value = "lisa". As expire time is not specified, this cookie will expire when the browser is closed.

<?php   setcookie('cookie2','electric1',time()+3600); ?>

This sets up a cookie with name = "cookie2" and value="electric1", and this cookies expires in 1 hour (3600 second).
Retrieve cookies
Cookies can be retrieved via the $_COOKIE or the $_HTTP_COOKIE_VARS arrays. Assuming that the name of the cookie is "cookie1", the value of the cookie is retrieved by $_COOKIE['cookie1'].
Delete cookies
To delete a cookie from a client computer, simply use the setcookie() function and set the expiration time as a time in the past. For example, the following code,

<?php setcookie('cookie1','lisa',1); ?>

will get rid of the cookie with name = "cookie1" and value = "lisa".


Previous Page->PHP-Forms || Next Page->PHP-Redirect

One of the main features in PHP is the ability to take user input and generate subsequent pages based on the input. In this page, we will introduce the mechanism by which data is passed in PHP.
Let's consider the following two files:
query.php

<form action=result.php type=post> <input type=text name=employee> <input type=submit value=Submit> </form>

result.php

<?php   $employee_name = $_POST["employee"];   print $employee_name; ?>

After the user types in a value in the text box and click on the Submit button in query.php, the result.php page will display the value that the user has just typed in.
How is this done? The $_POST function captures the value associated with the key "employee", which was specified in the input name attribute in query.php. The variable $employee_name is then set to the value for this key.
$_GET is $_POST's closely related cousin. The usage is exactly the same, except you'll need to use $_GET if the form action type is GET. When the form action type is GET, the parameters you submitted will be visible in the URL as the query string. In a POST method, no query string is visible in the URL.
Usually when using $_POST or $_GET, you'll want to first check to see if PHP has indeed received values for the key of interest. If not, you may want to assign the receiving variable some type of default value. To do this, we leverage the isset() function:

$result_variable = isset($_POST["key_value"],0,$_POST["key_value"]);

In the above example, if "key_value" is not set, $result_variable is set to 0.
Common input methods include text input, radio button, checkbox, and drop down menu


Previous Page->PHP-Array || Next Page->PHP-cookies

An array is a way of holding multiple closely-related values, such as the test scores of all students in a class. An array is made up of a key and a value, and the key points to the value.
There are two types of arrays: Indexed array and Associative array. Their difference is in the way the key is specified. Let's look at both of them:
Indexed Array
In an indexed array, the keys are numeric and starts with 0, and the values can be any data type. The following shows two ways of assigning values to an indexed array:

$friends = array("Sophie","Stella","Alice");

This is equivalent to the following:

$friends[0] = "Sophie"; $friends[1] = "Stella"; $friends[2] = "Alice";

Associative Array
In an associative array, the keys are not necessarily numeric, and even when they are numeric, not necessarily in any order. So, when you are putting data into an associative array, you'll need to make sure you specify both the key and the value:

$student_score = array("John"=>80, "Matt"=>90, "May"=>85);

This is equivalent to the following:

$student_score["John"] = 80; $student_score["Matt"] = 90; $student_score["May"] = 85;

Multidimensional Array
The arrays in the examples above are 1-dimensional. However, there will be times when multidimensional arrays are desired. What's a multidimensional array? That's when you have arrays of arrays. Let's look at an example below:

$array1 = array (10,15,20); $array2 = array (110,115,120); $array3 = array (210,215,220); $big_array = array ($array1, $array2, $array3);

$big_array is now a 2-dimensional array. For example, if you have the following output code:

print {$big_array[1,2]};

The output would be

120

Remember to use { } when you are accessing the value of a multidimensional array


Previous Page->PHP-Functions || Next Page->PHP-Forms

Similar to other programming languages, PHP provides a way for programmers to define functions, which can then be called elsewhere in the program. The syntax for a function is:
function "function_name" (arg1, arg2...)
{
  [code to execute]
  return [final_result];
}
where [final_result] is typically the variable holding the final value to be returned from the function.
Let's take a look at an example:

function double_this_number($input_number) {   return $input_number*2; }

Elsewhere in the PHP code, we have

$x = 10; $y = double_this_number($x); print $y;

The output will be

20

Previous Page->PHP-Functions || Next Page->PHP-Array

INCLUDE is used in PHP to append the code from an external file into the current file. The syntax for INCLUDE is
INCLUDE ("external_file_name");
This is a convenient feature for a large website. Often, we may want to change an element of the website that is consistent across the entire site, yet we don't want to go through the trouble of updating every single file. In this case, we can simply use INCLUDE in every file to call the same external file, and then all we need to change is the content in that one external file.
Let's look at a simple example. Assuming we have the following two files:
index.php

<?php   print "This is the original content<br>";   include ("external_file"); ?>

external_file

<?php   print "This is the external content"; ?>

Upon executing index.php, we'll get the following output:

This is the original content This is the external content

This is because, to the web server, it sees the following content:

<?php   print "This is the original content<br>";   print "This is the external content"; ?>

Previous Page->PHP-For-Loop || Next Page->PHP-Functions

FOR is used in PHP to execute the same code a set number of times. The basic syntax of FOR is as follows:
FOR (expression 1, expression 2, expression 3)
{
  [code to execute]
}
FOR tells PHP to first execute "expression 1", then evaluate "expression 2". If "expression 2" is true, then [code to execute] is executed. After this, expression 3 is executed, and then "expression 2" is evaluated again. If "expression 2" is true, then [code to execute] is executed for a second time. The cycle continues until "expression 2" is no longer true.
Let's look at an example. Assuming we have the following piece of code:

FOR ($i = 0; $i <= 2; $i++) {   print "value is now " . $i . "<br>"; }

The output of the above code is:

value is now 0 value is now 1 value is now 2

During the 1st iteration, $i = 0, which means the expression, ($i <= 2), is true. Therefore, the print statement is executed, and $i gets incremented by 1 and becomes 1.
During the 2nd iteration, $i = 1, which means the expression, ($i <= 2), is true. Therefore, the print statement is executed, and $i gets incremented by 1 and becomes 2.
During the 3rd iteration, $i = 2, which means the expression, ($i <= 2), is true. Therefore, the print statement is executed, and $i gets incremented by 1 and becomes 3.
During the 4th iteration, $i = 3, which means the expression, ($i <= 2), is false. Therefore, PHP exits out of the FOR loop, and does not execute the print statement.


DO .. WHILE is used in PHP to provide a control condition. The idea is to execute a piece of code while a condition is true. The basic syntax of DO .. WHILE is as follows:
DO {
  [code to execute]
} WHILE (conditional statement)
The difference between DO .. WHILE and WHILE is that DO .. WHILE will always execute the [code to execute] at least once, and in a WHILE construct, it is possible for the [code to execute] to never execute.
Let's look at an example. Assuming we have the following piece of code:

$i = 5 DO {   print "value is now " . $i . "<br>";   $i--; } WHILE ($i > 3);

The output of the above code is:

value is now 5 value is now 4

During the 1st iteration, $i = 5, the print statement is executed, $i gets decreased by 1 and becomes 4, then PHP checks the expression, ($i > 3), which turns out to be true. Therefore, the loop continues.
During the 2nd iteration, $i = 4, the print statement is executed, $i gets decreased by 1 and becomes 3, then PHP checks the expression, ($i > 3), which is no longer true. Therefore, PHP exits the loop.
If we change the above code to:

$i = 0 DO {   print "value is now " . $i . "<br>";   $i--; } WHILE ($i > 3);

The output would then be:

value is now 0

Even though the expression ($i > 3) is false from the very beginning, one line is still printed out because in DO .. WHILE, the code in the bracket following DO is always executed at least once.

FOREACH is used in PHP to loop over all elements of an array. The basic syntax of FOREACH is as follows:
FOREACH ($array_variable as $value)
{
  [code to execute]
}
or
FOREACH ($array_variable as $key => $value)
{
  [code to execute]
}
In both cases, the number of times [code to execute] will be executed is equal to the number of elements in the $array_variable array.
Let's look at an example. Assuming we have the following piece of code:

$array1 = array(1,2,3,4,5); FOREACH ($array1 as $abc) {   print "new value is " . $abc*10 . "<br>"; }

The output of the above code is:

new value is 10 new value is 20 new value is 30 new value is 40 new value is 50

The FOREACH loop above went through all 5 elements of array $array1, and each time prints out a statement containing 10x the array element value.


Previous Page->PHP-while-loop || Next Page->PHP-Include

WHILE is used in PHP to provide a control condition. The basic syntax of WHILE is as follows:
WHILE (expression)
{
  [code to execute]
}
WHILE tells PHP to execute the [code to execute] as long as the (expression) is true.
Let's look at an example. Assuming we have the following piece of code:

$counter = 8; WHILE ($counter < 10) {   print "counter is now " . $counter . "<br>";   $counter++; }

The output of the above code is:

counter is now 8 counter is now 9

During the first iteration, $counter = 8, which means the expression, ($counter < 10), is true. Therefore, the print statement is executed, and $counter gets incremented by 1 and becomes 9.
During the second iteration, $counter = 9, which means the expression, ($counter < 10), is true. Therefore, the print statement is executed, and $counter gets incremented by 1 and becomes 10.
During the third iteration, $counter = 10, which means the expression, ($counter < 10), is false. Therefore, the WHILE condition no longer is true, and the code in the bracket is no longer executed.

Previous Page->PHP-Switch || Next Page->PHP-For-loop

SWITCH is used in PHP to replace nested IF..ELSE loops, and is similar to the CASE command in other computer languages. The basic syntax of SWITCH is as follows:
SWITCH ($variable) {
CASE 'value 1':
  [code to execute when $variable = 'value 1']
  break;
CASE 'value 2':
  [code to execute when $variable = 'value 2']
  break;
CASE 'value 3':
...
DEFAULT:
  [code to execute when none of the CASE values matches $variable]
}
There can be an unlimited number of CASE conditions. In addition, DEFAULT is optional.
Let's view an example. Assuming we have the following piece of code:

$sample = 10; SWITCH ($sample) { CASE 30:   print "Value is 30";   break; CASE 25:   print "Value is 25";   break; CASE 20:   print "Value is 20";   break; DEFAULT:   print "Value is outside the range"; }

The output of the above code is:

Value is outside the range

This is because none of the CASE conditions was matched, so the code following DEFAULT is executed.

Previous Page->PHP-Else-if || Next Page->PHP-while-loop

In IF ELSE, PHP provides a way to do an either/or selection. What if you need more than two options? This is where ELSEIF comes in. ELSEIF is built on top of the IF ELSE construct to provide additional options. The basic syntax is as follows:
IF (conditional statement 1) {
  [code if condition statement 1 is true]
}
ELSEIF (conditional statement 2) {
  [code if condition statement 2 is true]
}
...
ELSE {
  [code if none of the above is true]
}
ELSEIF can be repeated as many times as needed prior to the ELSE statement.
Let's use an example. Assuming we have the following piece of code:

$sample = 10; IF ($sample > 15) {   print "Level 1"; } ELSEIF ($sample > 5) {   print "Level 2"; } ELSE {   print "Level 3"; }

The output of the above code is:

Level 2

This is because the first condition is false, and the second condition is true. Therefore, the code in the bracket after ELSEIF is executed.

Previous Page->PHP-if-else || Next Page->PHP-Switch

IF..ELSE is used in PHP to provide conditional judgements. The basic syntax is as follows:
IF (conditional statement) {
  [code if condition is true]
}
ELSE {
  [code if condition is false]
}
Let's see an example. Assuming we have the following piece of code:

$sample = 10; IF ($sample > 5) {   print "Number is greater than 5"; } ELSE {   print "Number is less than 5"; }

The output of the above code is:

Number is greater than 5

This is because the condition, ($sample > 5), is true. Therefore, the code in the bracket after IF is executed.

Previous Page->PHP-Operators || Next Page->PHP-else-if

The most common PHP operators are assignment operators, arithmetic operators, combined operators, comparison operators, and logical operators. Each type is discussed separately below.
Assignment Operators
The basic assignment operator in PHP is "=". This means that the operand to the left of "=" gets set to the value to the right of "=".
Arithmetic Operators

Operator	Example	Result
+	4 + 2	6
-	4 - 2	2
*	4 * 2	8
/	4 / 2	2
%	4 % 2	0
++	x = 4; x++;	x = 5
--	x = 4; x--;	x = 3

Combined Operators
You can combine an arithmetic operator with the assignment operator to form a combined operator. Combined operators are shown below:

Operator	Example	Meaning
+=	y += x	y = y + x
-=	y -= x	y = y - x
*=	y *= x	y = y * x
/=	y /= x	y = y / x
%=	y %= x	y = y % x

Comparison Operators

Operator	Meaning
==	is equal to
!=	is not equal to
>	is greater than
>=	is greater than or equal to
<	is less than
<=	is less than or equal to

Logical Operators

Operator	Meaning
||	or
&&	and
and	and
or	or
xor	xor
!	not

Previous Page->PHP-Variables || Next Page->PHP-if-else

Variable Types
Variables play an important role in PHP, as they are places for holding values. In PHP, there is no need to declare variables. Variable can hold eight different data types: bloolean, integer, float, string, array, object, resource, or NULL.
PHP is a weakly typed language. This means that variable type varies depending on what is stored in the variable at the time. For example, if we have a variable $a, when $a = 0, $a is an integer type variable. If later we set $a = "New", then $a becomes a string type variable.
Variable Name
A variable name always starts with a $, followed by a letter or an underscore. The rest of the variable name can be a letter, a number or an underscore.
For example, $dog is a valid variable name, while @dog is not (@dog does not start with a $).
Variables in PHP are case-sensitive. For example, $Employee and $employee are two different variables.
Variable Scope
In most cases, variables are local in scope. This means that variables declared within a function cannot be accessed outside of the function, and variables declared outside of a function cannot be access within the function.
To make a variable global, it must either be declared as global specifically, or it must be accessed using the $GLOBALS array

Previous Page->PHP-Introduction || Next Page->PHP-Operators

PHP is a recursive acronym for Hypertext Preprocessor. PHP stands for PHP: Hypertext Preprocessor, with that PHP standing for Personal Home Page [Tools].
PHP  is an open-source language, used primarily for dynamic web content and server-side applications.
 It is often pointed to as the main competitor with:

• Microsoft's C# - Visual Basic.NET - ASP family,
• Sun's Java - JSP
• Macromedia's ColdFusion
• CGI - Perl

It is a server-side scripting language whose main purpose is to generate the HTML code, which can be viewed by the client. As such, the PHP code itself is not visible to the clients (i.e., if you do a "view source" in your web browser, you cannot see the PHP code. You can only see the resulting HTML code). This contrasts with client-side languages such as Javascript, which is visible to the client.
PHP was first created by Rasmus Lerdorf in 1995, and saw its first official release in 1997. Milestone releases included PHP 3 in 1998, PHP 4 in 2000, and PHP 5 in 2004. Today, many large-scale websites run on PHP. The author was first introduced to PHP in 2000, and have found the language to be pretty easy to work with.
Below is a simple "Hello World" program, PHP flavor:

<?php   print "Hello World."; ?>

Executing this program on a web server enabled with PHP produces the following output:

Hello World.

PHP programs usually have an extension of .php.
By the end of this tutorial, you should have a good understanding of the basic constructs of PHP, as well as how PHP can interact with MySQL to produce dynamic web pages.

PHP-variables - -> Next Page

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