在C中使用需要任意数量参数的函数的参数 [英] Use the parameters of a function that takes any number of parameters, in C

问题描述

我刚刚阅读:"C无效参数" 关于这些函数定义之间的区别C:

I've just read: "C void arguments" about the differences between these function definitions in C:

int f(void)

和

int f()

理解第二种形式意味着一个返回带有任意数量参数的整数的函数，我想知道我们如何才能实际访问和使用这些未知参数?

Understanding that the second form means a function returning integer that takes any number of parameters, I wondered how can we actually access and use these unknown parameters?

我很想获得示例代码和说明.

I'd love to get sample code and explanation.

此外，我知道C语言中Varargs的机制(具有va_arg，va_end，va_start函数)，并且很高兴听到该机制与f()形式之间的区别.

Also, I know the mechanism of the Varargs in C (with va_arg, va_end, va_start functions) and would be glad to hear about the differences between this mechanism and the f() form mentioned above.

非常感谢！

推荐答案

int f(void)表示返回不带参数的int的函数.

int f(void) means a function returning int that takes no parameters.

您可以看到此示例，以了解使用int f()的结果

You can see this example to see the consequence of using int f()

#include <stdio.h>

void f();

int main() {
  f(); /* prints some garbage */
  f(16);  /* prints 16 */ 
  return 0;
}

void f(a1)
  int a1;
{
   printf("%d\n", a1);
}

还有这个:-

#include <stdio.h>
    #include <stdlib.h>
    int f();
    int f(int x) {
        return x;
    }
    int main (int argc, char *argv[]) {
         printf ("%d\n", f(atoi(argv[1])));
         return 0;
    }

pax> gcc -Wall --std=c99 -o qq qq.c
pax> ./qq 42
42

这篇关于在C中使用需要任意数量参数的函数的参数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！