c++ - 加法和整数除法的无效操作数错误？

Question

这是我的功能。我想知道为什么我不能对两个 int 变量执行简单的数学运算

int sockMerchant(int n, vector<int> ar) {
int pairs;

for (int i = 1; i <= 100 ; i++) { //for every number ("Color") between 1 and 100
    for (int j = 0; j < n; j++) { //iterate thru array to look for it
        if (ar[j] == i) { //once found,
            for (int k = j; k < n ; k++) { //count how many of that number is there
                if (ar[k] == i) {
                    int count;
                    count++;
                }
            }
        count = (count/2);
        pairs = (pairs+count);
        }
    }
}
return pairs;
}

这是收到的错误:

solution.cc: In function ‘int sockMerchant(int, std::vector<int>)’:
solution.cc:20:27: error: invalid operands of types ‘<unresolved overloaded 
function type>’ and ‘int’ to binary ‘operator/’
         count = (count/2);
                  ~~~~~^~
solution.cc:21:27: error: invalid operands of types ‘int’ and ‘<unresolved 
overloaded function type>’ to binary ‘operator+’
         pairs = (pairs+count);
                  ~~~~~^~~~~~

Answer 1

在 count = (count/2) 和 pairs = (pairs+count) 中，你指的不是 int 你声明是因为它不在范围内。您实际上指的是函数 std::count因为你在那个编译单元的某处有using namespace std;。这是你shouldn't do that的原因之一.

要解决此问题，您需要在适当的范围内声明 count:

int sockMerchant(int n, vector<int> ar) {
    int pairs;
    int count = 0;

    for (int i = 1; i <= 100 ; i++) { //for every number ("Color") between 1 and 100
        for (int j = 0; j < n; j++) { //iterate thru array to look for it
            if (ar[j] == i) { //once found,
                for (int k = j; k < n ; k++) { //count how many of that number is there
                    if (ar[k] == i) {
                        count++;
                    }
                }
            count = (count/2);
            pairs = (pairs+count);
            }
        }
    }
    return pairs;
}