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PHP Function Use Guide: Miscellaneous Functions and Constants

Reading time 4 min
Published Aug 8, 2017
Updated Oct 15, 2019

Explaining PHP function use is smoother when methods can be categorized into clear groups. However, some single functions and constants stand alone and don't belong to any specific categories.

Even though such functions are not a part of a chain of similar methods, they still need to be addressed. Therefore, we dedicate a tutorial to PHP miscellaneous functions.

PHP Function Use: Main Tips

  • PHP miscellaneous functions are functions which just don't fit into the other major categories.
  • They can prove useful in PHP configuration or other tasks.
  • Every function in this tutorial is a PHP built in function.

Runtime Configuration

The way PHP miscellaneous functions behave always depends on the settings inside the php.ini file. Let's have a look at the options we have for PHP configuration using miscellaneous functions:

Name Description Default value Changeable
ignore_user_abort FALSE will indicate that script is to be terminated as soon as the user tries to output something after the client has aborted their connection "0" PHP_INI_ALL
highlight.string Colored highlight for PHP string "#DD0000" PHP_INI_ALL
highlight.comment Colored highlight PHP comment "#FF8000" PHP_INI_ALL
highlight.keyword Colored highlight for PHP keyword (e.g. parenthesis, semicolon) "#007700" PHP_INI_ALL
highlight.bg Colors the background [Deprecated since PHP 5.4] "#FFFFFF" PHP_INI_ALL
highlight.default Set colored highlight to default color in PHP. "#0000BB" PHP_INI_ALL
highlight.html Colored highlight for HTML code. "#000000" PHP_INI_ALL
browscap Filename and directory of the browser-capabilities file (e.g. browscap.ini) NULL PHP_INI_SYSTEM

List of Methods

In this section, you will be informed of the PHP function use of this miscellaneous category. For instance, you can set a function to be executed later with the PHP sleep() method. There are many methods to analyze in the table below. However, we are sure that some of them will prove themselves to be useful.

Function Description
connection_aborted() Check whether client has disconnected
connection_status() Return current connection status
connection_timeout() Check whether script has timed out [Deprecated since PHP 4.0.5]
constant() Return value of constant
define() Define constant
defined() Check whether constant exists
die() Print message and exits current script
eval() Evaluate string as PHP code
exit() Print message and exits current script
get_browser() Return capabilities of user's browser
__halt_compiler() Halt compiler execution
highlight_file() Output file with PHP syntax highlighted
highlight_string() Output string with PHP syntax highlighted
ignore_user_abort() Set whether remote client can abort running of script
pack() Pack data into binary string
php_check_syntax() [Deprecated since PHP 5.0.5]
php_strip_whitespace() Return source code of file with PHP comments and whitespace deleted
show_source() Alias for the highlight_file() function
sleep() Delay code execution for number of seconds
sys_getloadavg() Get system load average
time_nanosleep() Delay code execution for number of seconds and nanoseconds
time_sleep_until() Delay code execution until specified time
uniqid() Generate unique ID
unpack() Unpack data from binary string
usleep() Delay code execution for number of microseconds

Predefined Constants

This list below contains the constant names, descriptions and versions in which these PHP constants can be executed:

Constant Description PHP version
CONNECTION_ABORTED Checks if the client has disconnected 4 and newer
CONNECTION_NORMAL Checks status of the connection 4 and newer
CONNECTION_TIMEOUT Checks if the connection has timed out 4.0.5. and older [Deprecated]
__COMPILER_HALT_OFFSET__ Checks byte position of the data start 5.1. and newer

PHP Function Use: Summary

  • All the functions that just don't seem to belong to any particular category are defined as PHP miscellaneous functions.
  • While they stand alone, every miscellaneous PHP built in function is still very useful in the process of PHP configuration.
  • If you are using PHP 5 or a newer version, none of these functions require installation.