CODEWITHSUNDEEP
c++stlstdmap
makurisan
makurisan

Reputation: 529

suspect result with std::map insert

I tried to use:

std::map<std::wstring, std::pair<std::wstring, INT_PTR>> mm;
**mm.insert(_T("name"), std::make_pair(_T("value1"), static_cast<INT_PTR>(1));**

What is wrong with that?

If I use this:

mm[_T("name")] = std::make_pair(_T("value1"), static_cast<INT_PTR>(1));

it works.

The error is this:

No constructor could take the source type, or constructor overload resolution was ambiguous

The same with that:

std::map<std::wstring, std::vector<std::pair<std::wstring, INT_PTR>>> mm;

std::vector <std::pair<std::wstring, INT_PTR>> vec;
vec.push_back(std::make_pair(_T("value1"), static_cast<INT_PTR>(1)));
mm.insert(_T("name"), vec);

Why does it work with "insert_or_assign" like this?

mm.insert_or_assign(_T("name"), vec);

Upvotes: 2

Views: 86

Answers (1)

acraig5075
acraig5075

Reputation: 10756

std::map::insert simply doesn't take the two parameters that you're attempting. It takes a one-parameter key-value pair.

mm.insert(std::make_pair(_T("name"), std::make_pair(_T("value1"), static_cast<INT_PTR>(1))));

std::map::insert_or_assign on the other hand does take the two parameters you're attempting.

Upvotes: 5

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