Phpunset () Description: This is the details page of php unset (). It introduces the knowledge, skills, and experience related to php, unset, and php unset, and some php source code.
Class = 'pingjiaf' frameborder = '0' src = 'http: // biancheng.dnbc?info/pingjia.php? Id = 361000 'Rolling = 'no'> 1. if multiple variable names direct to a variable value, the unset variable name only disconnects the variable name from the variable value and does not release the memory. this value still exists.
(For exceptions, see 2 ).
2. the memory will be released in both cases, otherwise the variable value still exists in the memory.
A) when the variable value occupies more than 256 bytes, unset () will be used to release the memory (this is the result of some tests, to be explained)
B) after all the variables pointing to this value (for example, a referenced variable points to this value) are destroyed
3. if you want to release the variable memory, you 'd better use $ a = NULL to release it. When NULL is assigned, this address is released, and all references pointing to this variable value are empty.
4. when a global variable is unset in a local environment, the global variable only fails in the local scope and remains unchanged elsewhere.
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Http://biancheng.dnbcw.info/php/361000.html pageNo: 1.
