选择使用模板排序，无效的字符串转换为int，C ++

Question

I am trying to do selection sort using a template, I originally coded it for vectors of type int then abstracted it with templates. When I try to use a vector of strings I get the error "No viable conversion from string to int".

I noticed that in my swap function I am using a temp variable of type int, how do you declare a temporary holding variable if you don't know what the value type of the variables will be?

I think the error is in the function swapval.

Also, how do I overload the operator to deal with multiple types? Do templates work for operator overloading?

Here is my code.

template<typename T>
void selection_sort(vector<T>& v)
{
    int next = 0;
    for (next = 0; next <  v.size() -1; next++)
    {
        int minpos = check_value(v, next, v.size() -1.0);

        if (minpos != next) {
            swapval( v[minpos], v[next]);
        }
    }
}

template<typename A, typename B>
void swapval(A& a, B& b)
{
    int temp = b; // temp value of int declared here, think this causes error
    b = a;
    a = temp;
}

template<typename T, typename A, typename B>
int check_value(vector<T>& v, A from, B to)
{
    int minpos = from;
    for (int i = from; i <= to; i++)
    {
        if (v[minpos] > v[i])
        {
            minpos = i;
        }
    }
    return minpos;
}

Answer 1

You should use a single type when swapping:

template<typename T>
void swapval(T& a, T& b)
{
    T temp = std::move(b);
    b = std::move(a);
    a = std::move(temp);
}