Simple program won't compile with qtcreator

Question

I installed qt 4.7.4 and gcc 4.6.1. I tried to compile this program but it won't compile for me:
Why cannot I compile this code?

#include <QApplication>
#include <iostream>
using std::cout;

int main(int argc, char** argv)
{
    QApplication app(argc,argv);
    int a[] = {1,2};
    for (auto e : a)
    {
        cout << e << '\n';
    }
    return app.exec();
}

Error:
C:...\main.cpp:9: error: 'e' does not name a type

I think I speak for everyone when I say we're sorry to hear that. What is your question? Care to tell us what the error was? — Widor, Nov 02 '11 at 12:48
@Widor the question (implicitly) is why cannot I compile it, but I'll update it. — smallB, Nov 02 '11 at 12:50
What command are you using to compile it? (your using c++11, and so you will need to tell g++ this via compiler flags: try `g++ file.cpp --std=c++0x`) — Tom, Nov 02 '11 at 12:53
Most probably your compiler does not understand this new c++ feature. — hochl, Nov 02 '11 at 12:56
@Tom where (via QTCreator) am I suppose to put those options — smallB, Nov 02 '11 at 13:02

score 4 · Accepted Answer · answered Nov 02 '11 at 12:54

4

for (auto e : a)
is a range based for loop from the c++11 standard. You need to enable the c++11 in gcc with the -std=c++0x command line.

answered Nov 02 '11 at 12:54

mkaes

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where (via QTCreator) am I suppose to put those options ? – smallB Nov 02 '11 at 13:03
I never used QtCreator. But this link should answer the question. http://stackoverflow.com/questions/2987062/configuring-the-gcc-compiler-switches-in-qt-qtcreator-and-qmake – mkaes Nov 02 '11 at 13:14
yes, this seems to solve the problem, great pity you cannot set it via some dialog. Thanks. – smallB Nov 02 '11 at 13:16

score 2 · Answer 2 · answered Nov 02 '11 at 12:57

2

For me this works (g++ 4.6.1, Qt 4.7.1):

g++ --std=c++0x -I$QTDIR/include/QtGui -I$QTDIR/include \
    test.cpp -L$QTDIR/lib -lQtCore -lQtGui

answered Nov 02 '11 at 12:57

hochl

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score 1 · Answer 3 · answered Nov 02 '11 at 12:55

1

You need --std=c++0x compiler flag.

answered Nov 02 '11 at 12:55

anio

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score 0 · Answer 4 · answered Nov 02 '11 at 12:53

0

My guess is that qtcreator (and qmake) does not feed the compiler with the flag instructing it to use C++2011.

answered Nov 02 '11 at 12:53

Didier Trosset

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score 0 · Answer 5 · answered Nov 02 '11 at 12:55

0

First, you want to be sure that your C++ file is compiled with the C++11 dialect (ie using -std=c++0x flag to g++) since you use the auto type inference feature.

Then, I think that your for loop might not be valid. Perhaps you want a to be a std::vector<int>

answered Nov 02 '11 at 12:55

Basile Starynkevitch

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Simple program won't compile with qtcreator

5 Answers5