VScode 中未定义的引用错误 [英] undefined reference error in VScode

问题描述

我正在测试如何在 C 中使用 extern，所以我为 main.c、test.c、headfile.h 创建了三个文件.我想在headfile.h中声明变量和函数，在test.c中定义，然后在main.c中打印出变量和调用函数它通过使用 Dev c++ 成功运行，但是，当我将完全相同的文件放入 VScode 时，它​​显示错误，即存在对变量的未定义引用

I'm testing the how to use extern in C ,so I create three files for main.c, test.c, headfile.h . I want to declare variable and function in headfile.h,define in the test.c ,then print out the variable and call function at the main.c It works successfully by using Dev c++,however, when I put the exact same files into VScode it show errors that there are undefined reference to variables

错误信息在此处输入图片描述

#include <stdio.h>
#include <stdlib.h>
#include"D:\My Documents\Desktop\CODE\c\VScode\externTest\headfile.h"
int gVar = 1;

int main(void)
{
    extern float a;

    printf("a = %f\n",a);
    printf("gVar = %d\n",gVar);
    printf("aa = %d\n",aa);
    printf("bb = %f\n",bb);
    function ();
    system("pause");
    return 0;
}

test.c

#include <stdio.h>
#include "D:\My Documents\Desktop\CODE\c\VScode\externTest\headfile.h" 
float a = 100;
int aa = 200;
float bb = 300;

void function (void){
    printf("yeh you got it!!\n");
    extern int gVar;
    gVar++;
    printf("gVar in test.c function = %d",gVar);
}

headfile.h

extern int aa;
extern float bb;
void function(void);

推荐答案

您的 main.c 文件似乎没有与 test.c 链接.我已经能够使用以下编译命令重现完全相同的错误消息:

It looks like your main.c file is not being linked with test.c. I have been able to reproduce the exact same error message using the following compilation commands:

$ gcc main.c
/tmp/ccVqEXL5.o: In function `main':
main.c:(.text+0x8): undefined reference to `a'
main.c:(.text+0x38): undefined reference to `aa'
main.c:(.text+0x51): undefined reference to `bb'
main.c:(.text+0x69): undefined reference to `function'
collect2: error: ld returned 1 exit status

要解决这个问题，只需通过执行 gcc main.c test.c 将您的 test.c 文件添加到编译中即可.

To fix this, simply add your test.c file to the compilation by either doing gcc main.c test.c.

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