CODEWITHSUNDEEP
c++
IUnknown
IUnknown

Reputation: 9809

C++ - updating values on maps

struct Instrument
{
   std::string   make;
   std::string   brand;
   double   age;
   Instrument(std::string const& f, std::string const& s, double   l) { BLABLA }
   bool operator<(Instrumentconst& rhs) { return BLABLABLA;}
};
std::map<int,Instrument>   instMap;

Instrument myObj();
instMap.insert(pair<int,Instrument>(10,myObj));

If I need to update a value in this map for individual attributes separately. Would we be creating copies of Instrument every time we retrieve it from map to update it?

it = instMap.lower_bound(10);
if (it != m.end())
    *(it->second).brand = "Jonas";<= will there be a copy of Instrument object created here?

Is this the most memory(and time) efficient way to update values - if this operation had to be done on a million entries?

We are using C++ 98.

Upvotes: 2

Views: 128

Answers (1)

wich
wich

Reputation: 17117

The simple answer is no, the Instrument object will not be copied.

The std::string will be copied, at least in c++98.

Upvotes: 3

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