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  1. class custom_cmp    {
  2. public:
  3. 	custom_cmp(const map<int, double> &_cmptable):cmptable(_cmptable){}
  4. 	bool operator()(const int &lhs, const int &rhs)
  5. 	{
  6. 		if(cmptable[lhs] > cmptable[rhs])
  7. 			return 1;
  8. 		else if(cmptable[lhs] == cmptable[rhs])
  9. 			return lhs < rhs;
  10. 		else return 0;
  11. 	}
  12. 	map<int, double> cmptable;
  13. };
  14.  
  15. class A
  16. {
  17. public:
  18.     // 如何在宣告class A object時也建立好內部map成員的比較函式
  19.     // 像main function宣告的方式一樣
  20. 	A(const map<int, double> &_cmptable):cmptable(_cmptable){}
  21.  
  22.     map<int, double> cmptable;
  23.     // 底下不行這樣寫
  24. 	custom_cmp cmpobject(cmptable);
  25. 	map< int, shared_ptr<char>, custom_cmp> header(cmpobject);
  26. };
  27.  
  28. int main(int argc, char *argv[])
  29. {
  30.     // 在main function內這樣宣告可以
  31.     map<int, double> cmptable;
  32.     custom_cmp cmpobject(cmptable);
  33.     map< int, shared_ptr<char>, custom_cmp> header(cmpobject);
  34.  
  35.     // 想在宣告A的物件時, Aobj內的header可根據cmptable來排序
  36.     A Aobj(cmptable);
  37.  
  38.     return 0;
  39. }
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https://ideone.com/y2Ue34
language:
C++ (gcc 8.3)
created:
13 years ago
visibility:
secret

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