Template argument deduction

The process of determining the types and values of the template arguments from the type of the function arguments is called template argument deduction.

int compare(const int &v1, const int &v2)
{
if (v1 < v2) return -1;
if (v2 < v1) return 1;
return 0;
}

int compare(const double &v1, const double &v2)
{
if (v1 < v2) return -1;
if (v2 < v1) return 1;
return 0;
}

int main()
{
compare(1, 0); // ok: binds template parameter to int
compare(3.14, 2.7); // ok: binds template parameter to double
return 0;
}

In the first call, compare(1, 0), those arguments are type int; in the second, compare(3.14, 2.7), they have type double.