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Annotation of coherent/a/usr/man/ALL/extern, revision 1.1

1.1     ! root        1: 
        !             2: 
        !             3: extern                      C Keyword                      extern
        !             4: 
        !             5: 
        !             6: 
        !             7: 
        !             8: Declare storage class
        !             9: 
        !            10: 
        !            11: extern indicates that a C element belongs to the _e_x_t_e_r_n_a_l storage
        !            12: class.  Both  variables and functions  may be declared  to be ex-
        !            13: tern.  Use of this keyword tells the C compiler that the variable
        !            14: or  function is  defined outside  of the  present file  of source
        !            15: code.  All  functions and variables defined  outside of functions
        !            16: are implicitly extern unless declared static.
        !            17: 
        !            18: When a  source file references  data that are  defined in another
        !            19: file, it must  declare the data to be extern,  or the linker will
        !            20: return an error message of the form:
        !            21: 
        !            22: 
        !            23:         undefined symbol _n_a_m_e
        !            24: 
        !            25: 
        !            26: For example, the following declares the array tzname:
        !            27: 
        !            28: 
        !            29:         extern char tzname[2][32];
        !            30: 
        !            31: 
        !            32: When  a function  calls  a function  that is  defined in  another
        !            33: source file or in a library, it should declare the function to be
        !            34: extern.  In  the absence of  a declaration, extern  functions are
        !            35: assumed to  return ints, which may cause  serious problems if the
        !            36: function actually returns a  32-bit pointer (such as on the 68000
        !            37: or i8086 LARGE model), a long, or a double.
        !            38: 
        !            39: For example, the function mmaalllloocc appears in a library and returns
        !            40: a pointer; therefore, it should be declared as follows:
        !            41: 
        !            42: 
        !            43:         extern char *malloc();
        !            44: 
        !            45: 
        !            46: If you do not do so,  the compiler assumes that mmaalllloocc returns an
        !            47: iinntt, and generate the error message
        !            48: 
        !            49: 
        !            50:         integer pointer pun
        !            51: 
        !            52: 
        !            53: when you attempt to use mmaalllloocc in your program.
        !            54: 
        !            55: ***** See Also *****
        !            56: 
        !            57: auto, C keywords, pun, register, static, storage class
        !            58: 
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        !            61: 
        !            62: 
        !            63: 
        !            64: COHERENT Lexicon                                           Page 1
        !            65: 
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