ANSI-C: maximum number of characters printing a decimal int

Question

I\'d like to know if it is an easy way of determining the maximum number of characters to print a decimal int.

I know contains

Answer 1

In C++11 and later, you can do the following:

namespace details {
    template
    constexpr size_t max_to_string_length_impl(T value) {
        return (value >= 0 && value < 10) ? 1                            // [0..9] -> 1
            : (std::is_signed::value && value < 0 && value > -10) ? 2 // [-9..-1] -> 2
            : 1 + max_to_string_length_impl(value / 10);                 // ..-10] [10.. -> recursion
    }
}

template
constexpr size_t max_to_string_length() { 
    return std::max(
        details::max_to_string_length_impl(std::numeric_limits::max()),
        details::max_to_string_length_impl(std::numeric_limits::min())); 
}