c++ - 全局变量“count”不明确

Question

#include <algorithm>
using namespace std;

int count = 0, cache[50];

int f(int n)
{  
    if(n == 2) count++;
    if(n == 0 || n==1) return n;
    else if (cache[n] !=- 1) return cache[n];
    else cache[n]= f(n-1) + f(n-2);
    return cache[n]; 
}

我在 gcc 4.3.4 中使用了这个函数，得到了以下错误：

prog.cpp: In function ‘int f(int)’:
prog.cpp:38: error: reference to ‘count’ is ambiguous

在我的本地机器（mingw32）上，我得到的错误是这个，虽然它不是针对int 'cache[]'.

有什么理由吗？

Answer 1

问题都是因为这里的第二行：

#include <algorithm>
using namespace std;

该行using namespace std带来了所有名称，<algorithm>其中还有一个名为 的函数count，并且在您的代码中，您已经声明了一个变量count。因此，模棱两可的错误。

解决方案是永远不要写using namespace std. 很糟糕很糟糕。

相反，请在您的代码中使用std::cout、std::cin、std::endl等。std::count

Answer 2

I think I may have figured this out. I have found that removing the using namespace std doesn't help, but when I change the name of the variable to something which is less common, like count can be changed to cnt or some personal versions like knt or isCycle. I don't exactly know what is the reason behind this.

Answer 3

yeah idk but changing the name to less common variable name works fine in case of mine

Answer 4

simply change the variable name as it 'count' matches the internal keyword while we declare using namespace std.