1 Python Determines whether a variable is defined

1 ## Python Determines if a variable has been defined2 3 detect if a variable is defined in Python4 5 The first method uses the built-in function locals ():6 locals (): Get Dictionary of defined objects7 8 'TestVar'   inchlocals (). Keys ()9 Ten The second method uses the built-in function dir (): One dir (): Get a list of defined objects A  - 'TestVar'   inchdir () -  the The third method uses the built-in function VARs (): - VARs (): Get Dictionary of defined objects -  -VARs (). Has_key ('TestVar') +  -  +Examples of----------------applications--------------------------------- A  at #TestVar Not defined - Print 'TestVar' inchlocals (). Keys () - #Output: False -  - Print 'TestVar' inchdir () - #Output: False in  - PrintVARs (). Has_key ('TestVar')   to #Output: False +  - #define TestVar theTestvar=1 *  $ Print 'TestVar' inchlocals (). Keys ()Panax Notoginseng #Output: True -  the Print 'TestVar' inchdir () + #Output: True A  the PrintVARs (). Has_key ('TestVar')   + #Output: True -  $------------------------------------- $ ##说明: - if the defined function has arguments, but no arguments are called, other errors are reported, not the wrong variables undefined!!!  - deffunc1 (srcdir): the     PrintSrcdir -     Wuyi Try: the func1 () - except: Wu     Print "1111"

1 Python Determines whether a variable is defined