Mixing C and C++/Qt code
- #ifdef SUM_H //this is sum.h
- extern "C"{
- #endif
- int mySum(int a,int b);
- #ifdef SUM_H
- }
- #endif // SUM_H
———————————————————————————————-
- #include "sum.h" //this is sum.c
- int mySum(int a, int b)
- {
- return a + b;
- }
————————————————————————————————————————————————————————————————
- #include <QtCore/QCoreApplication> // this is main.cpp
- #include <QDebug>
- #include "sum.h"
- int main(int argc, char *argv[])
- {
- int i = 5;
- int j = 6;
- int k;
- k = mySum(i,j);
- qDebug() << "this sum is " << k;
- return a.exec();
- }
———————————————————————————————————————————————————————————————
but it was wrong with /home/lovebingheji/qt/test-build-desktop-Qt_4_6_2_in_PATH__System__Release/../test/main.cpp:13: error: undefined reference to `mySum(int, int)’
——————————————————————————————————————————————————————————————-
but when i was iadd #include “sum.c” in main.cpp that is right
- #include <QtCore/QCoreApplication>
- #include <QDebug>
- #include "sum.h"
- #include "sum.c"
- int main(int argc, char *argv[])
- {
- int i = 5;
- int j = 6;
- int k;
- k = mySum(i,j);
- qDebug() << "this sum is " << k;
- return a.exec();
- }
—————————————————————————————————————————————————————————————————
why i just want main.cpp include “sum.h” but “sum.c” how can i should do ?
i create a QT console application project,please help me.thanks very much
2 replies
Welcome to the forums. Some housekeeping first:
- wrap code in @-tags or use the editor’s button. It makes your code look nicely and adds some pretty printing. I’ve added them for your, but please format yourself next time
- adding your question to quite old threads (the original thread [qt-project.org] dates back to October last year) isn’t that useful, better open a new thread with a decent topic. I’ve split your question off to a new thread for that reason.
- begging for private answers usually leads you to no answers at all. This is a public forum, with everyone answering in their spare times. We do not do private support. Read http://www.catb.org/~esr/faqs/smart-questions.html for some explanations
Regarding your actual question: The sum.h header file is plain wrong. Use this one
- #ifndef SUM_H
- #define SUM_H
- #ifdef __cplusplus
- extern "C" {
- #endif
- int mySum(int a, int b);
- #ifdef __cplusplus
- }
- #endif
- #endif // SUM_H
And then make sure that your sum.c implementation file is actually added to the list of source files and gets compiled and linked to your application.
You must log in to post a reply. Not a member yet? Register here!