php null empty

NULL

The special NULL value represents a variable with no value. NULL is the only possible value of type null.

A variable is considered to be null if:

  • it has been assigned the constant NULL.

  • it has not been set to any value yet.

  • it has been unset().


empty

emptyDetermine whether a variable is empty

Description

bool empty ( mixed $var )

Determine whether a variable is considered to be empty. A variable is considered empty if it does not exist or if its value equals FALSE. empty() does not generate a warning if the variable does not exist.

Returns FALSE if var exists and has a non-empty, non-zero value. Otherwise returns TRUE.

The following things are considered to be empty:

  • “” (an empty string)
  • 0 (0 as an integer)
  • 0.0 (0 as a float)
  • “0” (0 as a string)
  • NULL
  • FALSE
  • array() (an empty array)
  • $var; (a variable declared, but without a value)

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