How to make a char string from a C macro s value

Question

For example  how to avoid writing the  func name  twice    ifndef TEST FUN    define TEST FUN func name    define TEST FUN NAME  func name   endif   I d like to follow the Single Point of Truth rule   Version of C preprocessor     cpp --version cpp  GCC  4 1 2 20070626  Red Hat 4 1 2-14

User · Answer

include  lt stdio h gt    define QUOTEME x   x   ifndef TEST FUN    define TEST FUN func name    define TEST FUN NAME QUOTEME TEST FUN   endif  int main void        puts TEST FUN NAME       return 0      Reference  Wikipedia s C preprocessor page

User · Answer

Jonathan Leffler  Thank you  Your solution works   A complete working example       compile-time dispatch        gcc -Wall -DTEST FUN another func macro sub c -o macro sub  amp  amp    macro sub     include  lt stdio h gt    define QUOTE name   name  define STR macro  QUOTE macro    ifndef TEST FUN    define TEST FUN some func  endif   define TEST FUN NAME STR TEST FUN   void some func void      printf  some func   called n       void another func void      printf  do something else n       int main void      TEST FUN      printf  TEST FUN NAME  s n   TEST FUN NAME     return 0      Example     gcc -Wall -DTEST FUN another func macro sub c -o macro sub  amp  amp    macro sub do something else TEST FUN NAME another func

User · Answer

define TEST FUN NAME  FUNC NAME  see here

User · Answer

He who is Shy  gave you the germ of an answer  but only the germ   The basic technique for converting a value into a string in the C pre-processor is indeed via the     operator  but a simple transliteration of the proposed solution gets a compilation error    define TEST FUNC test func  define TEST FUNC NAME  TEST FUNC   include  lt stdio h gt  int main void        puts TEST FUNC NAME       return 0       The syntax error is on the  puts    line - the problem is a  stray    in the source   In section 6 10 3 2 of the C standard   The   operator   it says      Each   preprocessing token in the   replacement list for a function-like   macro shall be followed by a parameter   as the next preprocessing token in the   replacement list    The trouble is that you can convert macro arguments to strings -- but you can t convert random items that are not macro arguments   So  to achieve the effect you are after  you most certainly have to do some extra work    define FUNCTION NAME name   name  define TEST FUNC NAME  FUNCTION NAME test func    include  lt stdio h gt   int main void        puts TEST FUNC NAME       return 0       I m not completely clear on how you plan to use the macros  and how you plan to avoid repetition altogether   This slightly more elaborate example might be more informative   The use of a macro equivalent to STR VALUE is an idiom that is necessary to get the desired result    define STR VALUE arg        arg  define FUNCTION NAME name  STR VALUE name    define TEST FUNC      test func  define TEST FUNC NAME FUNCTION NAME TEST FUNC    include  lt stdio h gt   static void TEST FUNC void        printf  In function  s n   TEST FUNC NAME      int main void        puts TEST FUNC NAME       TEST FUNC        return 0           At the time when this answer was first written  shoosh s name used  Shy  as part of the name

User · Answer

define TEST FUN NAME  FUNC NAME  see here

User · Answer

He who is Shy  gave you the germ of an answer  but only the germ   The basic technique for converting a value into a string in the C pre-processor is indeed via the     operator  but a simple transliteration of the proposed solution gets a compilation error    define TEST FUNC test func  define TEST FUNC NAME  TEST FUNC   include  lt stdio h gt  int main void        puts TEST FUNC NAME       return 0       The syntax error is on the  puts    line - the problem is a  stray    in the source   In section 6 10 3 2 of the C standard   The   operator   it says      Each   preprocessing token in the   replacement list for a function-like   macro shall be followed by a parameter   as the next preprocessing token in the   replacement list    The trouble is that you can convert macro arguments to strings -- but you can t convert random items that are not macro arguments   So  to achieve the effect you are after  you most certainly have to do some extra work    define FUNCTION NAME name   name  define TEST FUNC NAME  FUNCTION NAME test func    include  lt stdio h gt   int main void        puts TEST FUNC NAME       return 0       I m not completely clear on how you plan to use the macros  and how you plan to avoid repetition altogether   This slightly more elaborate example might be more informative   The use of a macro equivalent to STR VALUE is an idiom that is necessary to get the desired result    define STR VALUE arg        arg  define FUNCTION NAME name  STR VALUE name    define TEST FUNC      test func  define TEST FUNC NAME FUNCTION NAME TEST FUNC    include  lt stdio h gt   static void TEST FUNC void        printf  In function  s n   TEST FUNC NAME      int main void        puts TEST FUNC NAME       TEST FUNC        return 0           At the time when this answer was first written  shoosh s name used  Shy  as part of the name

User · Answer

include  lt stdio h gt    define QUOTEME x   x   ifndef TEST FUN    define TEST FUN func name    define TEST FUN NAME QUOTEME TEST FUN   endif  int main void        puts TEST FUN NAME       return 0      Reference  Wikipedia s C preprocessor page

User · Answer

define TEST FUN NAME  FUNC NAME  see here

User · Answer

define TEST FUN NAME  FUNC NAME  see here

User · Answer

Jonathan Leffler  Thank you  Your solution works   A complete working example       compile-time dispatch        gcc -Wall -DTEST FUN another func macro sub c -o macro sub  amp  amp    macro sub     include  lt stdio h gt    define QUOTE name   name  define STR macro  QUOTE macro    ifndef TEST FUN    define TEST FUN some func  endif   define TEST FUN NAME STR TEST FUN   void some func void      printf  some func   called n       void another func void      printf  do something else n       int main void      TEST FUN      printf  TEST FUN NAME  s n   TEST FUN NAME     return 0      Example     gcc -Wall -DTEST FUN another func macro sub c -o macro sub  amp  amp    macro sub do something else TEST FUN NAME another func

User · Answer

include  lt stdio h gt    define QUOTEME x   x   ifndef TEST FUN    define TEST FUN func name    define TEST FUN NAME QUOTEME TEST FUN   endif  int main void        puts TEST FUN NAME       return 0      Reference  Wikipedia s C preprocessor page

User · Answer

Jonathan Leffler  Thank you  Your solution works   A complete working example       compile-time dispatch        gcc -Wall -DTEST FUN another func macro sub c -o macro sub  amp  amp    macro sub     include  lt stdio h gt    define QUOTE name   name  define STR macro  QUOTE macro    ifndef TEST FUN    define TEST FUN some func  endif   define TEST FUN NAME STR TEST FUN   void some func void      printf  some func   called n       void another func void      printf  do something else n       int main void      TEST FUN      printf  TEST FUN NAME  s n   TEST FUN NAME     return 0      Example     gcc -Wall -DTEST FUN another func macro sub c -o macro sub  amp  amp    macro sub do something else TEST FUN NAME another func

User · Answer

He who is Shy  gave you the germ of an answer  but only the germ   The basic technique for converting a value into a string in the C pre-processor is indeed via the     operator  but a simple transliteration of the proposed solution gets a compilation error    define TEST FUNC test func  define TEST FUNC NAME  TEST FUNC   include  lt stdio h gt  int main void        puts TEST FUNC NAME       return 0       The syntax error is on the  puts    line - the problem is a  stray    in the source   In section 6 10 3 2 of the C standard   The   operator   it says      Each   preprocessing token in the   replacement list for a function-like   macro shall be followed by a parameter   as the next preprocessing token in the   replacement list    The trouble is that you can convert macro arguments to strings -- but you can t convert random items that are not macro arguments   So  to achieve the effect you are after  you most certainly have to do some extra work    define FUNCTION NAME name   name  define TEST FUNC NAME  FUNCTION NAME test func    include  lt stdio h gt   int main void        puts TEST FUNC NAME       return 0       I m not completely clear on how you plan to use the macros  and how you plan to avoid repetition altogether   This slightly more elaborate example might be more informative   The use of a macro equivalent to STR VALUE is an idiom that is necessary to get the desired result    define STR VALUE arg        arg  define FUNCTION NAME name  STR VALUE name    define TEST FUNC      test func  define TEST FUNC NAME FUNCTION NAME TEST FUNC    include  lt stdio h gt   static void TEST FUNC void        printf  In function  s n   TEST FUNC NAME      int main void        puts TEST FUNC NAME       TEST FUNC        return 0           At the time when this answer was first written  shoosh s name used  Shy  as part of the name

User · Answer

Jonathan Leffler  Thank you  Your solution works   A complete working example       compile-time dispatch        gcc -Wall -DTEST FUN another func macro sub c -o macro sub  amp  amp    macro sub     include  lt stdio h gt    define QUOTE name   name  define STR macro  QUOTE macro    ifndef TEST FUN    define TEST FUN some func  endif   define TEST FUN NAME STR TEST FUN   void some func void      printf  some func   called n       void another func void      printf  do something else n       int main void      TEST FUN      printf  TEST FUN NAME  s n   TEST FUN NAME     return 0      Example     gcc -Wall -DTEST FUN another func macro sub c -o macro sub  amp  amp    macro sub do something else TEST FUN NAME another func

User · Answer

include  lt stdio h gt    define QUOTEME x   x   ifndef TEST FUN    define TEST FUN func name    define TEST FUN NAME QUOTEME TEST FUN   endif  int main void        puts TEST FUN NAME       return 0      Reference  Wikipedia s C preprocessor page

User · Answer

He who is Shy  gave you the germ of an answer  but only the germ   The basic technique for converting a value into a string in the C pre-processor is indeed via the     operator  but a simple transliteration of the proposed solution gets a compilation error    define TEST FUNC test func  define TEST FUNC NAME  TEST FUNC   include  lt stdio h gt  int main void        puts TEST FUNC NAME       return 0       The syntax error is on the  puts    line - the problem is a  stray    in the source   In section 6 10 3 2 of the C standard   The   operator   it says      Each   preprocessing token in the   replacement list for a function-like   macro shall be followed by a parameter   as the next preprocessing token in the   replacement list    The trouble is that you can convert macro arguments to strings -- but you can t convert random items that are not macro arguments   So  to achieve the effect you are after  you most certainly have to do some extra work    define FUNCTION NAME name   name  define TEST FUNC NAME  FUNCTION NAME test func    include  lt stdio h gt   int main void        puts TEST FUNC NAME       return 0       I m not completely clear on how you plan to use the macros  and how you plan to avoid repetition altogether   This slightly more elaborate example might be more informative   The use of a macro equivalent to STR VALUE is an idiom that is necessary to get the desired result    define STR VALUE arg        arg  define FUNCTION NAME name  STR VALUE name    define TEST FUNC      test func  define TEST FUNC NAME FUNCTION NAME TEST FUNC    include  lt stdio h gt   static void TEST FUNC void        printf  In function  s n   TEST FUNC NAME      int main void        puts TEST FUNC NAME       TEST FUNC        return 0           At the time when this answer was first written  shoosh s name used  Shy  as part of the name

[c] How to make a char string from a C macro's value?

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