undefinedp

来自「C实现的MUD,对大家基本入门网络游戏很有帮助!」· 代码 · 共 29 行

     uuuunnnnddddeeeeffffiiiinnnneeeeddddpppp((((3333))))          MMMMuuuuddddOOOOSSSS ((((5555 SSSSeeeepppp 1111999999994444))))           uuuunnnnddddeeeeffffiiiinnnneeeeddddpppp((((3333))))

     NNNNAAAAMMMMEEEE
          undefinedp() - determine whether or not a given variable is
          undefined.

     SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS
          int undefinedp( mixed arg );

     DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
          Return 1 if `arg' is undefined.  'arg' will be undefined in
          the following cases:

          1.   it is a variable set equal to the return value of a
               call_other to a non-existent method (e.g. arg =
               call_other(obj, "???")).

          2.   it is a variable set equal to the return value of an
               access of an element in a mapping that doesn't exist
               (e.g. arg = map[not_there]).

     SSSSEEEEEEEE AAAALLLLSSSSOOOO
          mapp(3), stringp(3), pointerp(3), objectp(3), intp(3),
          bufferp(3), floatp(3), functionp(3), nullp(3), errorp(3)

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