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Learn how to use the isset() function to check whether a variable is set and not NULL in PHP. See examples, syntax, parameters, return value and technical details.
Aug 2, 2021 · Learn how to use isset () to check if a variable is declared and is different than null. See examples, parameters, return values, notes and related functions.
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Apr 27, 2020 · Learn how to use the isset () function in PHP to check if a variable is declared and its value is not NULL. See syntax, parameters, return value and examples of the function.
- Introduction to The Php isset() Construct
- Using Php isset with Array
- Php isset() with String Offsets
- Php isset() with Multiple Variables
- Summary
PHP isset() returns true if a variable is set and not null. The isset() is a language construct, not a function. Therefore, you cannot assign it to a variable, return it from a function, or call it dynamically via a variable function. The following example will result in an error: Error: To work around it, you can create a function that uses the is...
If you pass an array element to isset(), it’ll return true. For example: Output: However, if you pass a non-existing element to isset(), it’ll return false. For example: Output: If you pass an array element with value null to isset(), The isset() will return false: Output:
The isset()works with string offsets. For example: Output: If you pass a string element with an invalid offset, the isset() will return false. For example: Output:
The isset() accepts multiple variables and returns true if all variables are set. The isset()evaluates the variables from left to right and stops when it encounters an unset variable. The following example returns true because all variables $x, $y and $zare set: Output: However, the following example returns false because the variable $y is null, w...
isset()is a language construct, not a function.isset() returns trueif a variable is set and not null.isset() returns trueif an array element exists and not null.isset() returns trueif a string index valid or false otherwise.Feb 21, 2023 · Learn how to use the isset function in PHP to check if a variable, array or array key is set or not. See the difference between isset and empty functions, and how to handle NULL values in PHP.
- Simplilearn
- Description
Jun 26, 2023 · The isset() function in PHP is extremely useful when you want to check if a variable has been defined or not. This function helps avoid errors caused by accessing uninitialized or undefined variables.
Aug 19, 2022 · The isset function is used to check whether a variable is set or not. If a variable is already unset with unset() function, it will no longer be set. The isset() function return false if testing variable contains a NULL value.
