7. Run-time polymorphism vs. parametric polymorphism

C++ also supports parametric polymorphism, also known as compile-time polymorphism:

• Unlimited number of polymorphic behaviors

• Programmer creates a template

• Compiler determines concrete implementation at compile-time.

For example,

template< typename ValueT >
void swap( ValueT& one, ValueT& another )
{
    ValueT temp = one;
    one = another;
    another = temp;
}

#include <cassert>

int main()
{
    double dbl1 = 0.1;
    double dbl2 = 0.2;
    swap( dbl1, dbl2 ); // swap two doubles
    assert( dbl1 == 0.2 && dbl2 == 0.1 );

    int int1 = 1;
    int int2 = 2;
    swap( int1, int2 ); // swap two integers
    assert( int1 == 2 && int2 == 1 );

    return 0;
}