Var_dump (): The ability to output the full information of a variable.
GetType (): Gets the type name of a variable, the result is a word (string), SetType (); Sets the type of a variable, syntax: SetType (variable name, target type)
Isset () Determines whether a variable has data:
Empty () to determine whether a data is empty: close to our daily concept (Nothing is empty)
Unset (): Destroys (deletes) a variable.
IS_XX type () series functions: Determine if a data is of a certain type, including: Is_int (), Is_float (), Is_numeric (), Is_bool (), Is_array (), Is_scalar ():
Is_numeric () to: 3, 3.5, "3", "3.14" is true
Is_scalar (): Determines whether it is a scalar type (that is, Int,float,stirng,bool)
The above describes the PHP type-related system functions, including the aspects of the content, I hope the PHP tutorial interested in a friend helpful.