example3_conditional_compilation.cpp

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#include <iostream>
#include <type_traits>

// Function for integral types
template <typename T>
typename std::enable_if<std::is_integral<T>::value, bool>::type
isEven(T value) {
    return value % 2 == 0;
}

// Function for floating-point types
template <typename T>
typename std::enable_if<std::is_floating_point<T>::value, bool>::type
isEven(T value) {
    return static_cast<int>(value) % 2 == 0;
}

int main() {
    std::cout << "Is 4 even? " << isEven(4) << std::endl;
    std::cout << "Is 5 even? " << isEven(5) << std::endl;
    std::cout << "Is 3.14 even? " << isEven(3.14) << std::endl;
    std::cout << "Is 4.0 even? " << isEven(4.0) << std::endl;

    // This would cause a compilation error:
    // isEven("not a number");

    return 0;
}