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Definition and Usage. The isset () function checks whether a variable is set, which means that it has to be declared and is not NULL. This function returns true if the variable exists and is not NULL, otherwise it returns false.
isset () determines if a variable is declared and is different than null. It returns true if the variable exists and has any value other than null, and false otherwise. See examples, notes, and related functions.
Learn how to use the PHP isset() construct to check if a variable is set and not null. See examples of using isset() with single or multiple variables, arrays, and strings.
24 wrz 2024 · The isset () function in PHP checks whether a variable is declared and not NULL. It returns true if the variable exists and has a non-NULL value, and false otherwise, without modifying the variable.
16 gru 2010 · Wielu początkujących programistów PHP ma problemy ze stosowaniem funkcji isset() oraz empty() – nie w każdej sytuacji potrafią jednoznacznie określić, jaką wartość powinny te funkcje zwracać dla określonych argumentów.
ISSET returns TRUE if the variable exists and has a value other than NULL. That means variables assigned a "", 0, "0", or FALSE are set, and therefore are TRUE for ISSET. EMPTY checks to see if a variable is empty.
Learn how to use the "isset" keyword in PHP to determine whether a variable is set and is not null. See syntax, examples, benefits and quiz questions.
