Szymon Marczak Szymon Marczak - 2 months ago 17
C++ Question

Filter typenames in C++

This is my converter to byte array (vector).

template<typename T>
void put(T value) {
int size = sizeof(value);

uint8_t *array;
array = reinterpret_cast<uint8_t *>(&value);

if (littleEndian) {
for (int i = 0; i < size; i++) {
arr.push_back(array[i]);
}
} else {
for (int i = size - 1; i >= 0; i--) {
arr.push_back(array[i]);
}
}
}


As you can see, this function accepts all variable types. Is it possible to filter typenames? E.g. I want to allow only
uint8_t, int8_t, uint16_t, int16_t etc. + float and double too
? I don't want to make 10
if
statements, because it doesn't look clean.

Answer

You can do this using std::is_integral and SFINAE. This will remove the template from consideration if the type is not a integer type. It would look something like

template<typename T, typename std::enable_if<std::is_integral<T>::value>::type* = nullptr>
void put(T value)
{
    // code
}

Live Example

If instead you want allow all integral and floating point types then you can use std::is_arithmetic like

template<typename T, typename std::enable_if<std::is_arithmetic<T>::value>::type* = nullptr>
void put(T value)
{
    // code
}