Question

The following is my environment:

• Eclipse IDE for C/C++ Developers(Juno)
• Qt 4.8.3
• Qt Eclipse Integration v1.6.1
• mingw(20120426)

When I create a Qt console project, I just can’t use C library functions, such as exit(int) or atoi(string).

The error message is such like Function 'exit' could not be resolved.

I have included stdlib.h, but still can’t work.

I don’t know if there is some relation with index.

---

20121109 Update

Thanks for give me help!

atoi is just a example!

Although I write program in c++, but sometimes I want use C library, so I tag it c++.

The following is what I include

• C:/MinGW/include
• C:/MinGW/lib/gcc/mingw32/4.6.2/include
• C:/MinGW/lib/gcc/mingw32/4.6.2/include/c++
• C:/MinGW/lib/gcc/mingw32/4.6.2/include/c++/backward
• C:/MinGW/lib/gcc/mingw32/4.6.2/include/c++/mingw32
• C:/MinGW/lib/gcc/mingw32/4.6.2/include-fixed

Others are Qt library.

And the following is main.

#include <QtCore>
#include <QCoreApplication>
#include <cstdlib>

using namespace std;

int main(int argc, char *argv[])
{
    std::exit(0);
    QCoreApplication a(argc, argv);
    return a.exec();
}

I try this way but still get error message Function 'exit' could not be resolved.

Thanks a lot!

Answer 1

First of all, use C++ headers style. For stdlib.h :

#include <cstdlib>

Then, I guess you’re not bringing namespace information. Either write :

using namespace std;

(even if I don’t recommend it) or

using std::exit    using std::atoi;

or use fully qualified names :

std::exit(-1);

Finally, why do you need such functions like atoi ?