Method of inserting into a map in c++11 and c++17?

Question

I created a map using

std::map<long,std::vector<long> > indices

When trying to insert a key and vector element with

indices.insert(std::pair<long,std::vector<long> >(0,{0,1,2}));

I get huge lines of error ending with

C:/TDM-GCC-64/lib/gcc/x86_64-w64-mingw32/5.1.0/include/c++/bits/stl_map.h:685:9: note:   template argument deduction/substitution failed:
Main.cpp:44:66: note:   candidate expects 2 arguments, 1 provided
     indices.insert(std::pair<long,std::vector<long> > (0,{0,1,2}));

if during compilation I do

g++ Main.cpp -std=c++17

However it compiles without any error with

g++ Main.cpp -std=c++11

Is the procedure different in c++17 ? If yes, what is it? Or am I missing something?

You should be using `std::pair >`. The first element of the pair (`value_type`) is a const object. — 1201ProgramAlarm, Feb 02 '20 at 19:20
Probably an error on the line above the one you posted. These locations are not always exact — n314159, Feb 02 '20 at 19:29
This may be some interaction between the mingw compiler and [`#include "bits/stdc++.h"'](https://stackoverflow.com/q/31816095/5231607). — 1201ProgramAlarm, Feb 02 '20 at 20:11

score 0 · Answer 1 · edited Feb 03 '20 at 16:29

0

Your above insert(std::pair<long,std::vector<long> >(0,{0,1,2})) looks fine. It should work if it is GNU C++ 17 I think as it worked in my case.

I think this following would also work now in C++17,

indices.insert({ {0},{{0,1,2}} });

C++ 17 has introduced a new overload to permit insert( { {key}, {value, args} } ) syntax.

edited Feb 03 '20 at 16:29

anatolyg

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answered Feb 02 '20 at 19:37

FahimAhmed

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Method of inserting into a map in c++11 and c++17?

1 Answers1