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Annotation of coherent/a/usr/man/ALL/_2323, revision 1.1.1.1

1.1       root        1: 
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                      3: ##                    Preprocessing Operator                   ##
                      4: 
                      5: 
                      6: 
                      7: 
                      8: Token-pasting operator
                      9: 
                     10: 
                     11: The preprocessing operator ## can be used in both object-like and
                     12: function-like  macros.   When  used  immediately  before  or  im-
                     13: mediately after  an element in  the macro's replacement  list, ##
                     14: joins  the corresponding  preprocessor token  with  its neighbor.
                     15: This is sometimes called ``token pasting''.
                     16: 
                     17: As an example of token pasting, consider the macro:
                     18: 
                     19: 
                     20:         #define printvar(number) printf("%s\n", variable ## number)
                     21: 
                     22: 
                     23: When the preprocessor reads the following line
                     24: 
                     25: 
                     26:         printvar(5);
                     27: 
                     28: 
                     29: it substitutes the following code for it:
                     30: 
                     31: 
                     32:         printf("%s\n", variable5);
                     33: 
                     34: 
                     35: The  preprocessor throws  away all  white  space both  before and
                     36: after the ##  operator.  This gives you an easy  way to print any
                     37: one of a set of strings.
                     38: 
                     39: ## must not  be used as the first or  last entry in a replacement
                     40: list.  All instances of  the ## operator are resolved before fur-
                     41: ther macro replacement is performed.
                     42: 
                     43: For more information on object-like and function-like macros, see
                     44: #define.
                     45: 
                     46: ***** See Also *****
                     47: 
                     48: #, #define, C preprocessor
                     49: 
                     50: ***** Notes *****
                     51: 
                     52: Token pasting  has been performed by separating  the tokens to be
                     53: pasted with an empty comment, but this is no longer necessary.
                     54: 
                     55: The order of evaluation of multiple ## operators is unspecified.
                     56: 
                     57: 
                     58: 
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                     61: 
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                     63: 
                     64: COHERENT Lexicon                                           Page 1
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