using struct as key in map

Question

i am using a map with key as 'tm structure' defined in time.h now when i'm using statement it=HashTime.find(tm structure object); where it is the iterator then i am getting error like:

no match for 'operator=' in '((const CTime*)this)->CTime::HashTime.std::map<_Key, _Tp, _Compare, _Alloc>::find [with _Key = tm, _Tp = long int, _Compare = CTime::compare, _Alloc = std::allocator<std::pair<const tm, long int> >, std::map<_Key, _Tp, _Compare, _Alloc>::const_iterator = std::_Rb_tree_const_iterator<std::pair<const tm, long int> >, key_type = tm](((const std::map<tm, long int, CTime::compare>::key_type&)((const std::map<tm, long int, CTime::compare>::key_type*)m_ntmDate))) = m_datesec'

what's the type of it and HashTime? and does it work if you use auto it = HashTime.find(...);? — PeterT
– PeterT, Commented Feb 3, 2012 at 6:43

pmr · Accepted Answer · 2012-02-03 11:40:20Z

1

This may help you:

#include <iostream> #include <map> struct valueInfo { int value1; int value2; int value3; valueInfo(const int A,const int B,const int C) : value1(A),value2(B),value3(C) {} }; class valueComp { public: bool operator()(const valueInfo& A, const valueInfo& B) const { return A.value2<B.value2; } }; typedef std::map<valueInfo,double,valueComp> MapCTYPE; int main() { MapCTYPE TMap; valueInfo B(1,2,3); valueInfo C(3,3,4); TMap.insert(MapCTYPE::value_type(B,4.5)); TMap.insert(MapCTYPE::value_type(C,8.4)); MapCTYPE::iterator vc=TMap.find(MapCTYPE::key_type(1,2,8)); if (vc!=TMap.end()) { std::cout<<"Success:"<<vc->second<<std::endl; } }

edited Feb 3, 2012 at 11:40

pmr

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answered Feb 3, 2012 at 11:35

Ashutosh

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3 Comments

Rishibha sharma Over a year ago

Thanks alot :) your post has solved my operator overloading errors.This is what the i have written : void MakeTime( struct tm &trf) { it =HashTime.find(trf); if( it == HashTime.end()) { m_datesec= mktime (&trf); HashTime[trf]= m_datesec; } else { HashTime.find(trf) ; } } private: map<struct tm,long int,valueComp> HashTime; map<struct tm,long int,valueComp>::iterator it; long int m_datesec; }; but i am getting error:no matching function for call to'Time::MakeTime(tm*)

Rishibha sharma Over a year ago

and i am calling the MakeTime function in other header file with strptime (strDate.c_str (), strFormat.c_str (), &m_tmDate); struct tm trf= m_tmDate; cobj.MakeTime(&trf); where m_tmDate is another tm structure having some values set for each of its variable.

Rishibha sharma Over a year ago

valueComp is the class with bool operator()(const tm &A,const tm &B) const and cobj is object of Time class..

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