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  1.     #include <iostream>
  2.  
  3.     template < unsigned N > constexpr
  4.     unsigned countarg( const char( &s )[N], unsigned i = 0, unsigned c = 0 )
  5.     {
  6.       return
  7.         s[i] == '\0'
  8.         ? i == 0
  9.         ? 0
  10.         : c + 1
  11.         : s[i] == ','
  12.         ? countarg( s, i + 1, c + 1 )
  13.         : countarg( s, i + 1, c );
  14.     }
  15.  
  16.     constexpr
  17.     unsigned countarg()
  18.     {
  19.       return 0;
  20.     }
  21.  
  22.     #define ARGC( ... ) countarg( #__VA_ARGS__ )
  23.  
  24.  
  25.     int main()
  26.     {
  27. 	  std::cout
  28. 	    << ARGC() << std::endl
  29. 	    << ARGC( 1 ) << std::endl
  30. 	    << ARGC( one, two ) << std::endl
  31. 	    << ARGC( "abc", 123, XYZ ) << std::endl
  32. 	    << ARGC( unknown = 0, red = 1, green = 2, blue = 4 ) << std::endl
  33. 	    << ARGC( "1", "2", "3", "4", "5" ) << std::endl
  34. 	    << "Wrong (comma must be escaped): " << ARGC( "This is a comma: ," ) << std::endl
  35. 	    << "Fine: " << ARGC( "This is a comma: \x2c" );
  36.  
  37.       return 0;
  38.     }
Success #stdin #stdout 0s 3468KB
comments ()
stdin 
Standard input is empty
stdout 
0
1
2
3
4
5
Wrong (comma must be escaped): 2
Fine: 1
https://ideone.com/b9SjIi
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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