When I try to compile the code below (in a Qt 4.8 using llvm-g++-4.2

Question

0

Asked: June 16, 20262026-06-16T08:51:37+00:00 2026-06-16T08:51:37+00:00

When I try to compile the code below (in a Qt 4.8 using llvm-g++-4.2

0

When I try to compile the code below (in a Qt 4.8 using llvm-g++-4.2 (GCC) 4.2.1), I get the following error:

../GLWidget.cpp:24:   instantiated from here
../GLWidget.cpp:24: error: explicit instantiation of 'std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const std::basic_string<_CharT, _Traits, _Alloc>&) [with _CharT = char, _Traits = std::char_traits<char>, _Alloc = std::allocator<char>]' but no definition available

What does this error mean, and what should I do to fix it?

Source code:

#include <iostream>
#include <fstream>
#include <string>

using namespace std;

void testOStream(){
    filebuf fb;
    fb.open ("test.txt",ios::out);
    std::ostream os(&fb);
    std::string test("test");
    os << test; // This line has the problem
    fb.close();
}