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PHP PHP Basics PHP on the Web Final Quiz

Kat Cuccia
Kat Cuccia
786 Points
Posted by Kat Cuccia
Kat Cuccia
786 Points

Why does a variable assigned one double quote test as a false boolean value?

One of the questions in the final quiz asks, "Which of the following variables would be considered FALSE when tested as a boolean?" The correct answer is $name = ";. Why on earth does a " result in false??

2 Answers

andren
andren
28,558 Points
andren
andren
28,558 Points

Because PHP (as well as many other languages) has certain values they consider "Truthy" and some which they consider "Falsy". As you might guess "Truthy" values are converted to the boolean true and "Falsy" are converted to false.

In the case of PHP there is a set list of values that are considered "Falsy", and any value that is not in that list are considered "truthy". Here is the list of "Falsy" values:

  • The boolean FALSE itself
  • The integer 0 (zero)
  • The float 0.0 (zero)
  • The empty string, and the string "0"
  • An array with zero elements
  • The special type NULL (including unset variables)
  • SimpleXML objects created from empty tags

Since $name is set to an empty string in the Quiz it is considered false.

Cristian Opran
Cristian Opran
6,963 Points
Cristian Opran
Cristian Opran
6,963 Points

good answer, thank you