Similarities and differences between isset() and !empty() functions in PHP-PHP Tutorial-php.cn

isset()and! The empty()function is similar, both will return the same result. But the only difference is! Theempty()function does not generate any warnings or electronic notifications when the variable does not exist. It's enough to use either function. By merging two functions into a program it causes time lapse and unnecessary memory usage.

1.isset()

isset ( mixed $var , mixed $... = ? ) : bool

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var: The variable to be checked.
Return value: If var exists and the value is not null, return true, otherwise return false.

PS:If a variable has been released usingunset(), it will no longer be isset(). Ifisset()is used to test a variable that is set to null, false will be returned. At the same time, it should be noted that thenullcharacter ("\0") is not equivalent to the null constant ofPHP. If multiple parameters are passed in at one time, thenisset()will only return when all parameters are settrueThe calculation process is from left to right, and when an unset variable is encountered midway will stop immediately.

"; // 声明一个空数组 $array = array(); echo isset($array['geeks']) ? 'array is set.' : 'array is not set.'; ?>

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Output:

0 is set with isset functionarray is not set. array is not set.

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##2.empty()

empty ( mixed $var ) : bool

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var: Variable to be checked
Return value: Return when var exists and is a non-empty and non-zero value
falseOtherwise returntrue.

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Output

0 is considered empty 1 is considered set

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The following content will be judged as empty:

"" (empty String)
0 (0 as an integer)
0.0 (0 as a floating point number)
"0" (0 as a string)
null

3. Similarities and differences between the twoisset() and

! The empty()

function is similar, both will return the same result. But the only difference is! Theempty()function does not generate any warnings or electronic notifications when the variable does not exist. It's enough to use either function. By merging two functions into a program it causes time lapse and unnecessary memory usage.

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0 is set with isset function 1 is set with !empty function

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