What does unset foo do in php
(PHP 4, PHP 5, PHP 7, PHP 8) Show unset — Unset a given variable DescriptionThe behavior of unset() inside of a function can vary depending on what type of variable you are attempting to destroy. If a globalized variable is unset() inside of a function, only the local variable is destroyed. The variable in the calling environment will retain the same value as before unset() was called.
The above example will output: To unset() a global variable inside of a function, then use the $GLOBALS array to do so:
If a variable that is PASSED BY REFERENCE is unset() inside of a function, only the local variable is destroyed. The variable in the calling environment will retain the same value as before unset() was called.
The above example will output: If a static variable is unset() inside of a function, unset() destroys the variable only in the context of the rest of a function. Following calls will restore the previous value of a variable.
The above example will output: Before unset: 1, after unset: 23 Before unset: 2, after unset: 23 Before unset: 3, after unset: 23 Parametersvar The variable to be unset. vars Further variables. Return ValuesNo value is returned. ExamplesExample #1 unset() example
Example #2 Using
The above example will output: Notes
See Also
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remove_element (&$array, $key) // pass array by reference phpmanual at kennel17 dot co dot uk ¶ 12 years ago
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f1() // example of invalid variable reference use muhamad_zakaria at yahoo dot com ¶ 17 years ago
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bar(){ What is set and unset in PHP?Purpose of isset in PHP
The isset function is used to check if a variable is set or not. That means it determines if a variable is assigned a value and is not null. Also, the isset PHP function checks if the given variable is not unset by using the unset function.
What's the difference between unset () and unlink ()?The unlink() function is used when you want to delete the files completely. The unset() Function is used when you want to make that file empty.
What's better at freeing memory with PHP unset () or $var Null?null variable:
It speedily frees the memory.
Does PHP unset free memory?unset() does just what its name says - unset a variable. It does not force immediate memory freeing. PHP's garbage collector will do it when it see fits - by intention as soon, as those CPU cycles aren't needed anyway, or as late as before the script would run out of memory, whatever occurs first.
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