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This is a list of 25 interesting PHP functions that are
useful in a variety of situations. Please do not make changes to
the actual set of functions without first discussing them on the
talk page.
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Contents
- 1
Function list
- 2
Ceil()
-
2.1 Usage
-
2.2 Practical
applications
-
2.3 See also
- 3
Count()
-
3.1 Usage
-
3.2 Practical
applications
- 4
Die()
-
4.1 Usage
-
4.2 Practical
applications
-
4.3 See also
- 5
Echo()
-
5.1 Usage
-
5.2 Practical
applications
- 6
Empty()
-
6.1 Usage
-
6.2 Practical
applications
-
6.3 Pitfall
- 7
Exit()
- 8
file_get_contents()
-
8.1 Usage
-
8.2 Practical
applications
- 9
file_put_contents()
-
9.1 Usage
-
9.2 Practical
applications
-
9.3 PHP4 Workaround
- 10
getenv()
-
10.1 Usage
-
10.2 Practical
applications
-
10.3 See also
- 11
header()
-
11.1 Usage
-
11.2 Practical
applications
-
11.3 See also
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Function list
Following is the raw list of 25, in alphabetical order:
- ceil()
- count()
- die()
- echo()
- empty()
- exit()
- file_get_contents()
- file_put_contents()
- getenv()
- header()
- htmlentities()
- include()
- ini_set()
- isset()
- mail()
- md5()
- mkdir()
- phpinfo()
- preg_match()
- print_r()
- rand()
- require()
- str_replace()
- str_len()
- trim()
Ceil()
float ceil (float value)
Rounds up the supplied float value to the next integer and
returns the result.
Usage
<?php
$a = 2.444;
echo ceil($a); // 3
?>
Practical applications
Can be used to check if a number divides evenly with another
- for example:
<?php
$num1 = 5;
$num2 = 7;
$div = $num2 / $num1;
if (ceil($div) == $div)
echo "$num2 divides into $num1 evenly.";
else
echo "$num2 does not divide into $num1 easily ($div).";
?>
See also
- Floor() - function that does the opposite
Count()
int count (mixed var)
Returns an integer value of the number of elements in the
supplied variable - generally an array, as anything else will
return 1.
Usage
<?php
$stuff[0] = 4;
$stuff[1] = 3;
$stuff[2] = 2;
echo count($stuff); // 3
?>
Practical applications
Handling every element of an array - for example:
<?php
$values[] = 5;
$values[] = 3;
$values[] = 6;
$values[] = -1;
$num = count($values);
for ($i=0; $i < $num + 1; $i++) $values[$i] += 2;
?>
Bear in mind that this could be done without count() using
the foreach case structure anyway.
Die()
void die ([string status])
Terminates the current script execution. If parameter
'status' is specified, also displays 'status' in an error
message. Alias for exit().
Usage
<?php
if (!file_get_contents("stats.txt")) die("Could not fetch statistics history.");
?>
Practical applications
Terminating the script if a database connection cannot be
opened.
<?php
mysql_connect("localhost","root","") or die("Could not connect to database server.");
?>
See also
- Exit() - function that does exactly the same thing, but
sounds slightly more graceful
Echo()
void echo (string outputstring)
Outputs data to the current stream (console, apache request
etc.). Is more a language construct than a function, and can
therefore be used without the parenthesis.
Usage
<?php
echo("Some text."); // Will output 'Some text.'
echo "Some text."; // Will output 'Some text.' just as above
?>
Practical applications
<?php
if ( $_SESSION['loggedin'] )
{
echo "Welcome, " . $_SESSION['username'];
}
else
{
echo "Access denied. This area is for members only. Please login.";
}
?>
Empty()
bool empty (mixed var)
Used to check if a variable is empty. Note: It is used to
only check variables, thus empty(trim($var)); will result in a
parse error.
Usage
<?php
$var = 'Hello';
if (empty($var))
echo 'The variable is empty';
else
echo 'The variable is not empty'; // True in this case
?>
Practical applications
<?php
$name = $_POST['name'];
if (empty($name))
echo 'You need to enter your name';
?>
Pitfall
0 is considered empty.
<?php
$var = 0;
if (empty($var))
echo 'The variable is empty'; // True in this case
else
echo 'The variable is not empty';
?>
Exit()
void exit ( [String status] )
void exit ( int status )
Exactly the same as die.
file_get_contents()
String file_get_contents ( String filename [, boolean
use_include_path [, resource context [, int offset [, int
maxlen]]]] )
Reads a file into a string.
Usage
<?php
echo file_get_contents('my_file.txt');
?>
Practical applications
<?php
$contents = file_get_contents('data.txt');
echo $contents; // Would output whatever is in the file
?>
file_put_contents()
int file_put_contents ( string filename, mixed data , int
flags , resource context )
Writes data to a file. The flags can be
FILE_USE_INCLUDE_PATH, FILE_APPEND and/or LOCK_EX.
Note: This is a PHP5 function only.
Will return false on failure, or the number of bytes written
to the file.
Usage
<?php
file_put_contents('my_file.txt', 'Hello', FILE_APPEND); // Will append 'Hello' to the specified file
?>
Practical applications
<?php
$ip = $_SERVER['REMOTE_ADDR']; // Get client's IP address
file_put_contents('ips.txt', "\n",$ip, FILE_APPEND);
?>
PHP4 Workaround
There is nothing really special about this function, except
it saves your time (it basically calls fopen, fwrite and
fclose). Here is something that can be used for making sure your
PHP script works with PHP5 and PHP4:
<?php
if (function_exists('file_put_contents') === false)
{
function file_put_contents($file, $data)
{
$fh = @fopen($file, 'w');
if ($fh === false)
return false;
else
{
fwrite($fh, $data);
fclose($fh);
return true;
}
}
}
?>
This is of course a very basic replacement and does not take
into account any flags which goes beyond the scope of this
document.
getenv()
string getenv ( string varname)
Returns the value of an environment variable
Usage
<?php
echo getenv('HTTP_USER_AGENT'); //will output what web browser is currently viewing the page
?>
Practical applications
Allows you to execute commands based on server information
<?php
if (strpos(getenv('HTTP_USER_AGENT'), "Mozilla") > 0)
{
// Execute Mozilla specific code
}
?>
See also
- apache_getenv()
- phpinfo()
- putenv()
- Superglobals
header()
void header (string string [, bool replace
[, int http_response_code]] )
Updates the HTTP headers that are sent to the web browser
Usage
<?php
header("Cache-Control: no-cache");
?>
Practical applications
One use for the header fuction is to redirect the browser to
a diffrent web site
<?php
if ($_POST['username'] == "")
{
header("Location: http://my.url.com");
exit;
}
// Redirects the browser to http://my.url.com
?>
Another is to change how the browser will interpret the data
that is sent to it
<?php
header("Content-Type: text/xml")
echo '<?xml version="1.0" encoding="ISO-8859-1" ?>';
// Rest of XML output
?>
See also
- HTTP/1.1 specification
- headers_sent()
- setcookie()
