使用extern关键字调用函数 [英] Using extern keyword to call functions

问题描述

我想从其他调用c.test.c中定义的函数.

I want to call functions defined in test.c from other.c.

我可以extern function1调用它吗?另外，我是否必须在function2和function3中使用extern，它们被function1调用?

Can I extern the function1 to call it? Also, do I have to use extern in function2 and function3, which are being called by function1?

other.c

extern function1();
function1();

test.c

void function1()
{
    function2();
    function3();
}

void function2()
{

}

void function3()
{

}

推荐答案

实际上，默认情况下，每个函数都是extern :)-除非您声明它们不是:).如果您在第一次调用之前就拥有了原型，就足够了；

Actually every function by default is extern :) - unless you declare them to be not :). It is enough if you have the prototype before the first call;

int xxx(int, int, float, double);  // prototype


int main(void)
{
  int x,y;
  float z;
  double v;

  xxx(x,y,z,v);

  return 0;
}

---

该功能可以位于另一个.c文件中.您需要将目标文件包括在链接中.

---

Function can be in the another .c file. You need to include the object file to the linking.

int xxx(int a, int b, float c, double d)
{
  int result;
  /* do something */

  return result;
}

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