Do you guys see any problems in this simple code:

struct Timer
{
std::chrono::time_point<std::chrono::steady_clock> start, end;
std::chrono::duration<float> duration;

Timer()
{
start = std::chrono::high_resolution_clock::now();
}

~Timer()
{
end = std::chrono::high_resolution_clock::now();
duration = end - start;

float ms = duration.count() * 1000.0f;
std::cout << "Timer took: " << ms << "ms\n";
}
};

This code compiles with clang++ and even Visual Studio (Visual Studio
2022 Developer Command Prompt v17.12.3) but g++ gives many errors such
as this:

g++ -o Program2.exe -Wall main.cpp
main.cpp: In constructor 'Timer::Timer()':
main.cpp:16:65: error: no match for 'operator=' (operand types are 'std::chrono::time_point<std::chrono::_V2::steady_clock, std::chrono::duration<long long int, std::ratio<1, 1000000000> > >' and 'std::chrono::_V2::system_clock::time_point' {aka 'std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long long int, std::ratio<1, 1000000000> > >'})
16 | start = std::chrono::high_resolution_clock::now();
| ^
In file included from C:/msys64/ucrt64/include/c++/14.1.0/chrono:41,
from main.cpp:2: C:/msys64/ucrt64/include/c++/14.1.0/bits/chrono.h:922:13: note:
candidate: 'constexpr
std::chrono::time_point<std::chrono::_V2::steady_clock, std::chrono::duration<long long int, std::ratio<1, 1000000000> > >& std::chrono::time_point<std::chrono::_V2::steady_clock, std::chrono::duration<long long int, std::ratio<1, 1000000000> >

::operator=(const

std::chrono::time_point<std::chrono::_V2::steady_clock, std::chrono::duration<long long int, std::ratio<1, 1000000000> > >&)'
922 | class time_point
| ^~~~~~~~~~ C:/msys64/ucrt64/include/c++/14.1.0/bits/chrono.h:922:13: note: no
known conversion for argument 1 from 'std::chrono::_V2::system_clock::time_point' {aka 'std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long long int, std::ratio<1, 1000000000> > >'} to
'const std::chrono::time_point<std::chrono::_V2::steady_clock, std::chrono::duration<long long int, std::ratio<1, 1000000000> > >&' C:/msys64/ucrt64/include/c++/14.1.0/bits/chrono.h:922:13: note:
candidate: 'constexpr
std::chrono::time_point<std::chrono::_V2::steady_clock, std::chrono::duration<long long int, std::ratio<1, 1000000000> > >& std::chrono::time_point<std::chrono::_V2::steady_clock, std::chrono::duration<long long int, std::ratio<1, 1000000000> >

::operator=(std::chrono::time_point<std::chrono::_V2::steady_clock, std::chrono::duration<long long int, std::ratio<1, 1000000000> > >&&)' C:/msys64/ucrt64/include/c++/14.1.0/bits/chrono.h:922:13: note: no

known conversion for argument 1 from 'std::chrono::_V2::system_clock::time_point' {aka 'std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long long int, std::ratio<1, 1000000000> > >'} to 'std::chrono::time_point<std::chrono::_V2::steady_clock, std::chrono::duration<long long int, std::ratio<1, 1000000000> > >&&'
main.cpp: In destructor 'Timer::~Timer()':
main.cpp:21:63: error: no match for 'operator=' (operand types are 'std::chrono::time_point<std::chrono::_V2::steady_clock, std::chrono::duration<long long int, std::ratio<1, 1000000000> > >' and 'std::chrono::_V2::system_clock::time_point' {aka 'std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long long int, std::ratio<1, 1000000000> > >'})
21 | end = std::chrono::high_resolution_clock::now();
| ^ C:/msys64/ucrt64/include/c++/14.1.0/bits/chrono.h:922:13: note:
candidate: 'constexpr
std::chrono::time_point<std::chrono::_V2::steady_clock, std::chrono::duration<long long int, std::ratio<1, 1000000000> > >& std::chrono::time_point<std::chrono::_V2::steady_clock, std::chrono::duration<long long int, std::ratio<1, 1000000000> >

::operator=(const

std::chrono::time_point<std::chrono::_V2::steady_clock, std::chrono::duration<long long int, std::ratio<1, 1000000000> > >&)'
922 | class time_point
| ^~~~~~~~~~ C:/msys64/ucrt64/include/c++/14.1.0/bits/chrono.h:922:13: note: no
known conversion for argument 1 from 'std::chrono::_V2::system_clock::time_point' {aka 'std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long long int, std::ratio<1, 1000000000> > >'} to
'const std::chrono::time_point<std::chrono::_V2::steady_clock, std::chrono::duration<long long int, std::ratio<1, 1000000000> > >&' C:/msys64/ucrt64/include/c++/14.1.0/bits/chrono.h:922:13: note:
candidate: 'constexpr
std::chrono::time_point<std::chrono::_V2::steady_clock, std::chrono::duration<long long int, std::ratio<1, 1000000000> > >& std::chrono::time_point<std::chrono::_V2::steady_clock, std::chrono::duration<long long int, std::ratio<1, 1000000000> >

::operator=(std::chrono::time_point<std::chrono::_V2::steady_clock, std::chrono::duration<long long int, std::ratio<1, 1000000000> > >&&)' C:/msys64/ucrt64/include/c++/14.1.0/bits/chrono.h:922:13: note: no

known conversion for argument 1 from 'std::chrono::_V2::system_clock::time_point' {aka 'std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long long int, std::ratio<1, 1000000000> > >'} to 'std::chrono::time_point<std::chrono::_V2::steady_clock, std::chrono::duration<long long int, std::ratio<1, 1000000000> > >&&'

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On 17/12/2024 06:52, Bonita Montero wrote:

Am 17.12.2024 um 05:39 schrieb Student Project:

Do you guys see any problems in this simple code:
struct Timer
{
    std::chrono::time_point<std::chrono::steady_clock> start, end;
    std::chrono::duration<float> duration;

    Timer()
    {
        start = std::chrono::high_resolution_clock::now();

    std::chrono::time_point<std::chrono::high_resolution_clock> start, end;

    }

    ~Timer()
    {
        end = std::chrono::high_resolution_clock::now();
        duration = end - start;

        float ms = duration.count() * 1000.0f;
        std::cout << "Timer took: " << ms << "ms\n";
    }
};

That's while steady_clock and system_clock are the same with MSVC
(both rely on GetSystemTimeAsFileTime()).

Vielen Dank, Bonita. Es lässt sich jetzt in allen drei Compilern
kompilieren, auf die ich Zugriff habe. Das vollständige, einfache
Programm zum Ausprobieren finden Sie hier:

#include <iostream>
#include <chrono>
#include <thread>

/*
* Compile directives:
For g++:
g++ -std=c++20 -Wall -o obj/main.o -c src/main.cpp
g++ -std=c++20 -Wall -o Program obj/main.o

For clang++:
clang++ -o Program01.exe -Wall main.cpp

For Visual Studio:
cl /EHsc main.cpp

*/

struct Timer
{

std::chrono::time_point<std::chrono::high_resolution_clock> start, end;
std::chrono::duration<float> duration;

Timer()
{
start = std::chrono::high_resolution_clock::now();
}

~Timer()
{
end = std::chrono::high_resolution_clock::now();
duration = end - start;

float ms = duration.count() * 1000.0f;
std::cout << "Timer took: " << ms << "ms\n";
}
};

void Function()
{

Timer timer;
for (int i = 0; i < 1000; i++)
{
std::cout << "Hello World!\n";
}
}

int main()
{
Function();
}


Frohe Weihnachten.

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