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There is no corresponding function to call std :: vector <std :: tuple> push_back

I have an example program containing 6 time points using high_resolution_clock::now() from the standard chrono header. I take the difference in / in each of them, which leads to 3 differences and cast them as auto duration1 = std::chrono::duration_cast<std::chrono::microseconds>( t2 - t1 ).count(); to microseconds.

I have another variable called durations, which is assigned as follows: auto durations = std::make_tuple(duration1,duration2,duration3); containing previous time differences.

I need to insert this tuple into a vector, so I entered std::vector<std::tuple<std::chrono::microseconds,std::chrono::microseconds,std::chrono::microseconds>> list; However, when using list.push_back(durations); I get an error message:

 prog.cpp: In function 'int main()': prog.cpp:36:29: error: no matching function for call to 'std::vector<std::tuple<std::chrono::duration<long long int, std::ratio<1ll, 1000000ll> >, std::chrono::duration<long long int, std::ratio<1ll, 1000000ll> >, std::chrono::duration<long long int, std::ratio<1ll, 1000000ll> > > >::push_back(std::tuple<long long int, long long int, long long int>&)' list.push_back(durations);

I tried to find here std::chrono::microseconds and other std::chrono::duration stuff here , but failed to fix the problem.

I know this has something to do with my type system negligence, but I cannot find this error. Any help would be appreciated, and here is an ideal link .

 #include <iostream> #include <chrono> #include <vector> #include <tuple> using namespace std; using namespace std::chrono; void function() { long long number = 0; for( long long i = 0; i != 2000000; ++i ) { number += 5; } } int main() { high_resolution_clock::time_point t1 = high_resolution_clock::now(); high_resolution_clock::time_point t3 = high_resolution_clock::now(); high_resolution_clock::time_point t5 = high_resolution_clock::now(); function(); high_resolution_clock::time_point t2 = high_resolution_clock::now(); high_resolution_clock::time_point t4 = high_resolution_clock::now(); high_resolution_clock::time_point t6 = high_resolution_clock::now(); auto duration1 = std::chrono::duration_cast<std::chrono::microseconds>( t2 - t1 ).count(); auto duration2 = std::chrono::duration_cast<std::chrono::microseconds>( t4 - t3 ).count(); auto duration3 = std::chrono::duration_cast<std::chrono::microseconds>( t6 - t5 ).count(); auto durations = std::make_tuple(duration1,duration2,duration3); std::vector<std::tuple<std::chrono::microseconds,std::chrono::microseconds,std::chrono::microseconds>> list; list.push_back(durations); cout << duration1 << " -- "<< duration2 << " -- "<< duration3 << " -- "; return 0; }
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4 answers

You created a tuple of 3 integers, and you are trying to add it to a vector of 3 durations.

I take the difference for each of them, which leads to 3 differences and cast them as auto duration1 = std::chrono::duration_cast<std::chrono::microseconds>( t2 - t1 ).count(); to microseconds.

Why do you call count() for duration after duration_cast executed to convert to microseconds?

Just save the values ​​as microseconds objects and you can add them to the vector:

 auto duration1 = std::chrono::duration_cast<std::chrono::microseconds>( t2 - t1 ); auto duration2 = std::chrono::duration_cast<std::chrono::microseconds>( t4 - t3 ); auto duration3 = std::chrono::duration_cast<std::chrono::microseconds>( t6 - t5 );
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The type std::chrono::microseconds::count() not std::chrono::microseconds , it is some type of signed integral.

 auto duration1 = std::chrono::duration_cast<std::chrono::microseconds>( t2 - t1 ).count(); //decltype(duration1) is not std::chrono::microseconds

Thus, you cannot use the variables duration*n* for a vector that expects a microsecond value.

Easy to fix, just put off your count call until you try to print the contents.

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It is simple: do not call count .

std::chrono::microseconds is (in your case) a typedef for the type std::chrono::duration<long long int, std::ratio<1ll, 1000000ll> > . It is also the type that you get from running std::chrono::duration_cast<std::chrono::microseconds>( t2 - t1 ) .

However, this is not what you assign duration1 . You assign the result of calling the count function of this type. And this returns the number of ticks as a number ( long long int in your standard library case), and not as duration .

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You get a type mismatch.

 auto duration1 = std::chrono::duration_cast<std::chrono::microseconds>( t2 - t1 ).count()

Actually gives you a long long in your case, not std::chrono::microseconds . You can fix this using decltype() and changing

 std::vector<std::tuple<std::chrono::microseconds,std::chrono::microseconds,std::chrono::microseconds>> list;

For

 std::vector<decltype(durations)> list;

Living example

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