GCC编译相关 - HeavyYuan/A-CD-Record-Management-System GitHub Wiki

编译命令： gcc -c -o main.o main.c

/* main.c */
#include <stdio.h>

int main()
{
   int *p = foo();
}

When you invoke GCC, it normally does preprocessing, compilation, assembly and linking. The "overall options" allow you to stop this process at an intermediate stage. For example, the -c option says not to run the linker. Then the output consists of object files output by the assembler.（man gcc）

上述编译命令，没有报错foo undefined

去掉-c就会报错foo undefined。

解决办法也简单，对函数foo做下声明。