PHP File Handling

The fopen() function is used to open files in PHP.

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Opening a File

The fopen() function is used to open files in PHP.
The first parameter of this function contains the name of the file to be opened and the second parameter specifies in which mode the file should be opened:

$file=fopen("welcome.txt","r"); ?>

The file may be opened in one of the following modes:

Modes	Description
r	Read only. Starts at the beginning of the file
r+	Read/Write. Starts at the beginning of the file
w	Write only. Opens and clears the contents of file; or creates a new file if it doesn't exist
w+	Read/Write. Opens and clears the contents of file; or creates a new file if it doesn't exist
a	Append. Opens and writes to the end of the file or creates a new file if it doesn't exist
a+	Read/Append. Preserves file content by writing to the end of the file
x	Write only. Creates a new file. Returns FALSE and an error if file already exists
x+	Read/Write. Creates a new file. Returns FALSE and an error if file already exists

Note: If the fopen() function is unable to open the specified file, it returns 0 (false).

Example

The following example generates a message if the fopen() function is unable to open the specified file:

$file=fopen("welcome.txt","r") or exit("Unable to open file!"); ?>

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Closing a File

The fclose() function is used to close an open file:

$file = fopen("test.txt","r"); //some code to be executed fclose($file); ?>

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Check End-of-file

The feof() function checks if the "end-of-file" (EOF) has been reached.

The feof() function is useful for looping through data of unknown length.
Note: You cannot read from files opened in w, a, and x mode!

if (feof($file)) echo "End of file";

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Reading a File Line by Line

The fgets() function is used to read a single line from a file.
Note: After a call to this function the file pointer has moved to the next line.

Example

The example below reads a file line by line, until the end of file is reached:

$file = fopen("welcome.txt", "r") or exit("Unable to open file!"); //Output a line of the file until the end is reached while(!feof($file))   {   echo fgets($file). " ";   } fclose($file); ?>

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Reading a File Character by Character

The fgetc() function is used to read a single character from a file.
Note: After a call to this function the file pointer moves to the next character.

Example

The example below reads a file character by character, until the end of file is reached:
$file=fopen("welcome.txt","r") or exit("Unable to open file!");
while (!feof($file))
  {
  echo fgetc($file);
  }
fclose($file);
?>

PHP Include File

Server Side Includes (SSI)

You can insert the content of one PHP file into another PHP file before the server executes it, with the include() or require() function.
The two functions are identical in every way, except how they handle errors:

• include() generates a warning, but the script will continue execution
• require() generates a fatal error, and the script will stop

These two functions are used to create functions, headers, footers, or elements that will be reused on multiple pages.
Server side includes saves a lot of work. This means that you can create a standard header, footer, or menu file for all your web pages. When the header needs to be updated, you can only update the include file, or when you add a new page to your site, you can simply change the menu file (instead of updating the links on all your web pages).

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PHP include() Function

The include() function takes all the content in a specified file and includes it in the current file.
If an error occurs, the include() function generates a warning, but the script will continue execution.

Example 1

Assume that you have a standard header file, called "header.php". To include the header file in a page, use the include() function:

Welcome to my home page! Some text.

Example 2

Assume we have a standard menu file, called "menu.php", that should be used on all pages:

Home Tutorials References Examples About Us Contact Us

All pages in the Web site should include this menu file. Here is how it can be done:

Welcome to my home page. Some text.

If you look at the source code of the page above (in a browser), it will look like this:

Home Tutorials References Examples About Us Contact Us Welcome to my home page! Some text.

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PHP require() Function

The require() function is identical to include(), except that it handles errors differently.
If an error occurs, the include() function generates a warning, but the script will continue execution. The require() generates a fatal error, and the script will stop.

Error Example include() Function

include("wrongFile.php"); echo "Hello World!"; ?>

Error message:

Warning: include(wrongFile.php) [function.include]: failed to open stream: No such file or directory in C:\home\website\test.php on line 5 Warning: include() [function.include]: Failed opening 'wrongFile.php' for inclusion (include_path='.;C:\php5\pear') in C:\home\website\test.php on line 5 Hello World!

Notice that the echo statement is executed! This is because a Warning does not stop the script execution.

Error Example require() Function

Now, let's run the same example with the require() function.

require("wrongFile.php"); echo "Hello World!"; ?>

Error message:
Warning: require(wrongFile.php) [function.require]:
failed to open stream:
No such file or directory in C:\home\website\test.php on line 5

Fatal error: require() [function.require]:
Failed opening required 'wrongFile.php'
(include_path='.;C:\php5\pear')
in C:\home\website\test.php on line 5

PHP Date() Function

The PHP date() function is used to format a time and/or date.

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The PHP Date() Function

The PHP date() function formats a timestamp to a more readable date and time.
A timestamp is a sequence of characters, denoting the date and/or time at which a certain event occurred.

Syntax

date(format,timestamp)

Parameter	Description
format	Required. Specifies the format of the timestamp
timestamp	Optional. Specifies a timestamp. Default is the current date and time

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PHP Date() - Format the Date

The required format parameter in the date() function specifies how to format the date/time.
Here are some characters that can be used:

• d - Represents the day of the month (01 to 31)
• m - Represents a month (01 to 12)
• Y - Represents a year (in four digits)

A list of all the characters that can be used in the format parameter, can be found in our PHP Date reference.
Other characters, like"/", ".", or "-" can also be inserted between the letters to add additional formatting:

echo date("Y/m/d") . " "; echo date("Y.m.d") . " "; echo date("Y-m-d") ?>

The output of the code above could be something like this:

2009/05/11 2009.05.11 2009-05-11

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PHP Date() - Adding a Timestamp

The optional timestamp parameter in the date() function specifies a timestamp. If you do not specify a timestamp, the current date and time will be used.
The mktime() function returns the Unix timestamp for a date.
The Unix timestamp contains the number of seconds between the Unix Epoch (January 1 1970 00:00:00 GMT) and the time specified.

Syntax for mktime()

mktime(hour,minute,second,month,day,year,is_dst)

To go one day in the future we simply add one to the day argument of mktime():

$tomorrow = mktime(0,0,0,date("m"),date("d")+1,date("Y")); echo "Tomorrow is ".date("Y/m/d", $tomorrow); ?>

The output of the code above could be something like this:
Tomorrow is 2009/05/12

PHP $_POST Function

The built-in $_POST function is used to collect values in a form with method="post".

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The $_POST Function

The built-in $_POST function is used to collect values from a form sent with method="post".
Information sent from a form with the POST method is invisible to others and has no limits on the amount of information to send.
Note: However, there is an 8 Mb max size for the POST method, by default (can be changed by setting the post_max_size in the php.ini file).

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When to use method="post"?

Information sent from a form with the POST method is invisible to others and has no limits on the amount of information to send.
However, because the variables are not displayed in the URL, it is not possible to bookmark the page.

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The PHP $_REQUEST Function

The PHP built-in $_REQUEST function contains the contents of both $_GET, $_POST, and $_COOKIE.
The $_REQUEST function can be used to collect form data sent with both the GET and POST methods.

Example

Welcome !

You are years old.

PHP $_GET Function

The built-in $_GET function is used to collect values in a form with method="get".

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The $_GET Function

The built-in $_GET function is used to collect values from a form sent with method="get".
Information sent from a form with the GET method is visible to everyone (it will be displayed in the browser's address bar) and has limits on the amount of information to send (max. 100 characters).

PHP Forms and User Input

The PHP $_GET and $_POST variables are used to retrieve information from forms, like user input.

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PHP Form Handling

The most important thing to notice when dealing with HTML forms and PHP is that any form element in an HTML page will automatically be available to your PHP scripts.

Example

The example below contains an HTML form with two input fields and a submit button:

Name: Age:

When a user fills out the form above and click on the submit button, the form data is sent to a PHP file, called "welcome.php":
"welcome.php" looks like this:

Welcome ! You are years old.

Output could be something like this:
Welcome John!
You are 28 years old.

PHP Functions

The real power of PHP comes from its functions.

In PHP, there are more than 700 built-in functions.

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PHP Built-in Functions

For a complete reference and examples of the built-in functions, please visit our PHP Reference.

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PHP Functions

In this chapter we will show you how to create your own functions.
To keep the script from being executed when the page loads, you can put it into a function.
A function will be executed by a call to the function.
You may call a function from anywhere within a page.

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Create a PHP Function

A function will be executed by a call to the function.

Syntax

function functionName() { code to be executed; }

PHP function guidelines:

• Give the function a name that reflects what the function does
• The function name can start with a letter or underscore (not a number)

Example

A simple function that writes my name when it is called:

function writeName() { echo "Kai Jim Refsnes"; } echo "My name is "; writeName(); ?>

Output:

My name is Kai Jim Refsnes

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PHP Functions - Adding parameters

To add more functionality to a function, we can add parameters. A parameter is just like a variable.
Parameters are specified after the function name, inside the parentheses.

Example 1

The following example will write different first names, but equal last name:

function writeName($fname) { echo $fname . " Refsnes. "; } echo "My name is "; writeName("Kai Jim"); echo "My sister's name is "; writeName("Hege"); echo "My brother's name is "; writeName("Stale"); ?>

Output:

My name is Kai Jim Refsnes. My sister's name is Hege Refsnes. My brother's name is Stale Refsnes.

Example 2

The following function has two parameters:

function writeName($fname,$punctuation) { echo $fname . " Refsnes" . $punctuation . " "; } echo "My name is "; writeName("Kai Jim","."); echo "My sister's name is "; writeName("Hege","!"); echo "My brother's name is "; writeName("Ståle","?"); ?>

Output:

My name is Kai Jim Refsnes. My sister's name is Hege Refsnes! My brother's name is Ståle Refsnes?

 

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PHP Functions - Return values

To let a function return a value, use the return statement.

Example

function add($x,$y)
{
$total=$x+$y;
return $total;
}

echo "1 + 16 = " . add(1,16);
?>