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  1. #include <iostream>
  2.  
  3. template<typename T>
  4. struct traits1{
  5.   static T add(T a, T b) { return a+b; } /* default */
  6.   static T mul(T a, T b);                /* no default */
  7. };
  8.  
  9.  
  10. template<typename T>
  11. struct traits2{
  12.   static T add(T a, T b);
  13.   static T mul(T a, T b);
  14. };
  15.  
  16. template<>
  17. int traits2<int>::add(int a, int b) { return a*b; }
  18.  
  19. int main()
  20. {
  21.   std::cout << traits1<int>::add(40, 2) << "\n";
  22.  
  23.   // error: mul is not a member of traits1<int>
  24.   std::cout << traits1<int>::mul(40, 2) << "\n";
  25.  
  26.   std::cout << traits2<int>::add(40, 2) << "\n";
  27.   // error: undefined reference to traits2<int>::mul(int, int)
  28.   std::cout << traits2<int>::mul(40, 2) << "\n";
  29.   return 0;
  30. }
Compilation error #stdin compilation error #stdout 0s 0KB
comments (?)
stdin
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Standard input is empty
compilation info 
/home/XWFTpj/cckiScdw.o: In function `main':
prog.cpp:(.text+0x8a): undefined reference to `traits1<int>::mul(int, int)'
prog.cpp:(.text+0xf2): undefined reference to `traits2<int>::mul(int, int)'
collect2: ld returned 1 exit status
stdout
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Standard output is empty
https://ideone.com/uCeJz
language:
C++ (gcc 8.3)
created:
11 years ago
visibility:
secret

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