Приведение к старшему типу

// C++ Function template

#include <iostream>

using namespace std;

template <typename T>
T maximum(T& a, T& b)
{
    return a > b ? a : b;
}

int main()
{
    int m = 1, n = 2;
    cout << m << '\t' << n << endl;
    cout << "maximum(int, int) = " << maximum(m, n) << endl;
    double x = 3.4, y = 5.6;
    cout << x << '\t' << y << endl;
    cout << "maximum(double, double) = " << maximum(x, y) << endl;
    char A = 'A', B = 'B';
    cout << A << '\t' << B << endl;
    cout << "maximum(char, char) = " << maximum(A, B) << endl;
    return 0;
}

// C++ Function template

#include <iostream>

using namespace std;

template <typename T1, typename T2>
T1 maximum(T1 a, T2 b)
{
    return a > T1(b) ? a : T1(b);
}

template <typename T1, typename T2>
T2 minimum(T1 a, T2 b)
{
    return T2(a) < b ? T2(a) : b;
}

int main()
{
    int m = 1, n = 2;
    double x = 3.4, y = 5.6;
    cout << m << '\t' << n << endl;
    cout << "maximum(int, int) = " << maximum(m, n) << endl;
    cout << x << '\t' << y << endl;
    cout << "maximum(double, double) = " << maximum(x, y) << endl;
    cout << m << '\t' << x << endl;
    cout << "maximum(int, double) = " << maximum(m, x) << endl;
    cout << "maximum(double, int) = " << maximum(x, m) << endl;
    cout << n << '\t' << y << endl;
    cout << "minimum(int, double) = " << minimum(n, y) << endl;
    cout << "minimum(double, int) = " << minimum(y, n) << endl;
    return 0;
}