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Chapter 11. Control Structures |
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The require_once() statement includes and
evaluates the specified file during the execution of the script. This is a behavior similar to the
require() statement, with the only difference being that
if the code from a file has already been included, it will not be included again. See the
documentation for require() for more information on how
this statement works.
require_once() should be used in cases
where the same file might be included and evaluated more than once during a particular execution of
a script, and you want to be sure that it is included exactly once to avoid problems with function
redefinitions, variable value reassignments, etc.
For examples on using require_once() and
include_once(), look at the PEAR code included in the latest PHP source code
distributions.
Note: require_once() was added in PHP
4.0.1pl2
See also: require(), include(),
include_once(), get_required_files(),
get_included_files(), readfile(), and
virtual().
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