变量参数C ++ [英] variable arguments C++

问题描述

我正在努力学习C ++;问题来自可变参数，程序编写如下： -

I m trying to learn C++; the problem comes with variable arguments the program is written as below:-

#include<iostream>
#include"stdarg.h"
using namespace std;
int sum(int count,...)
{
	if(count<=0)
		return 0;
	va_list arg_ptr;
	va_start(arg_ptr,count);
	
	int s=0;
	for(int i=0;i<count;i++)
	
		s+=va_arg(arg_ptr,int);
		

	va_end(arg_ptr);
	return s;

}

int main()

{
cout << sum(2,4,6) << endl;// runs fime as cout << sum(2,4) output is 6 fine but cout << sum(2,4,6) gives output 10
//which i suppose must be 12
cin.get();
cin.ignore();
}

推荐答案

总和（2,4,6）的输出应该是10而不是12 ...你的第一个参数是其余参数的计数器。如果您希望答案为12，则应致电 sum（3,2,4,6）

The output from sum(2,4,6) should be 10 not 12 ... your first parameter is a counter for the rest of the parameters. If you want the answer to be 12 you should call sum(3,2,4,6)

您好。



对于总和（2,4,6），10是正确的结果。

对于总和（2,4），6是错误的。 />
sum函数的第一个参数（count）告诉我们将跟随多少个数字，所以...



sum（2,4,6） ）告诉总和2个数字，哪个值是4和6，总共10个。

sum（2,4）告诉sum2数字，但第二个没有提供，所以它将被读取从错误的内存位置（可能来自存储第一个参数，当前为2的堆栈位置）。



sum（2,4）应该用sum替换（1,4）。



问候，

Daniele。

Hi.

For sum(2,4,6), 10 is correct result.
For sum(2,4), 6 is wrong.
The first argument (count) of the sum function tells how many numbers will follow, so ...

sum(2,4,6) tells to sum 2 numbers which values are 4 and 6, for a total of 10.
sum(2,4) tells to sum2 numbers, but the second is not provided, so it will be read from a wrong memory location (probably from the stack location where the first argument, currently 2, is stored).

sum(2,4) should be replaced with sum(1,4).

Regards,
Daniele.

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