C++ 中的编译错误：对“main”collect2 的未定义引用：错误：ld 返回 1 个退出状态

Question

The command I'm running in Linux terminal is:

g++ -c main.cpp fraction.cpp ; g++ -WALL -o main.o fraction.o 

The full output of what is returned is:

/usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-   
gnu/Scrt1.o: In function `_start':
(.text+0x20): undefined reference to `main'
collect2: error: ld returned 1 exit status

The main.cpp was written by my professor, and he is checking our fraction class against it, so the main shouldn't have an error.

Answer 1

g++ -WALL -o main.o fraction.o

This command instructs your compiler to link fraction.o and create a file called main.o . Except that main.o was, of course, the result of compiling main.cpp .

Your obvious intent is to link both main.o and fraction.o into a new executable. You need to specify the name of the executable file you wish to create, using the -o option, and only then list both of your object files.

But, of course, you will likely need to recompile main.cpp , first.