如何以简单的方式从 C++ 的循环中删除最后一个逗号?

This program is for printing prime numbers till the input given and separating every prime number with a comma.

void main(){

    int N, counter=0, isPrime;

    int k, j;

    cout << "Enter maximum range: ";

    cin >> N;

    for (j=2; j<=N; j++){

        isPrime = 0;
        k = 2;

        while (k<j){

            if (j%k==0){

                isPrime++;
            }
            k++;
        }
        if (isPrime==0){

            if (k==N){
                cout << j;
            }
            else{
                cout << j << ",";
            }
            counter++;
        }
    }
    cout << endl;
    system("pause");
}

它只删除素数输入的最后一个逗号，而不删除任何其他输入.我该如何解决这个问题?

Input: 23
Output: 2,3,5,7,11,13,17,19,23
Input: 8
Output: 2,3,5,7,
Input: 9
Output: 2,3,5,7,

std::string delim = "";
for( auto&& item : vec )
{
   std::cout << delim << item;
   delim = ",";
}