C++ error detected

[Ran_Flora]

I have installed qt creator on ubuntu 20.04 using those commands line :

sudo apt install qtcreator

sudo apt install qt5-default

sudo apt install build-essential

Every time i use c++ it make errors like for example when i create a plain c++ application from the beginning of this main code

#include <iostream>

int main()
{
    std::cout << "Hello World!" << std::endl;
    return 0;
}

it give those error :

/work/QT project/PlainCppApp/main.cpp:2: error: expected a type      
/work/QT project/PlainCppApp/main.cpp:2: error: expected unqualified-id 
/work/QT project/PlainCppApp/main.cpp:2: error: expected '}'   /usr/include/c++/9/ostream:42: to match this '{'
  /work/QT project/PlainCppApp/main.cpp:5: error: no member named 'cout' in namespace 'std'   

I want to use c++ 17 because i have some library from this version i have to use, and i want gcc compiler but it always use clang
Thank you in advance.

[SGaist]

Hi,

Since you want to use the C++17 standard, did you request it ?
Are you using qmake or cmake ?

[Ran_Flora]

Hi, I am using CMake but even if i choose qmake i have the same errors for that simple code and i didn't find how to request c++17 standard

[JonB]

@Ran_Flora
qmake: CONFIG += c++1z
camke: Not sure, seems to vary by compiler, e.g. for gcc see https://stackoverflow.com/a/77408925/489865 ?

[Christian Ehrlicher]

What puzzles me is the error in line 2 - are you sure your system headers are correct and not screwed up somehow? This looks not like a problem with your code you are showing.

[Ran_Flora]

I have create a new project and i capture all the steps and i change the standard to 17 in the cmake here are the captures and you can see those errors.

from the beginning is the qt5-default stable and the installation is right or not for ubuntu 20.04

[JonB]

@Ran_Flora
As @Christian-Ehrlicher has said, the error message about "missing } for {" immediately after #include <iostream> makes it seem like that file (or something it includes) is somehow incorrect.....