Convert a char16_t to long/integer, (atoi / atol equivalent)

Question

I want to convert a char16_t to an integer and/or a long.

const char16_t* t = u"12";
long lt = atol( t);

Does such a function not exist?

Answer 1

Try this function: (it's not necessarily the most efficient solution, but it gets the job done if you have no choice (i.e. you have to have a char16_t* as input) and you're sure that you actually have a valid sequence of digits in your char16_t* string)

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#include <codecvt>
#include <locale>
#include <string>

int char16_to_int(const char16_t* s16)
{
    // https://stackoverflow.com/a/7235204/865719
    std::wstring_convert<std::codecvt_utf8_utf16<char16_t>, char16_t> convert;
    std::string str = convert.to_bytes(s16);

    return std::stoi(str);
}

long char16_to_long(const char16_t* s16)
{
    // https://stackoverflow.com/a/7235204/865719
    std::wstring_convert<std::codecvt_utf8_utf16<char16_t>, char16_t> convert;
    std::string str = convert.to_bytes(s16);

    return std::stol(str);
}

EDIT: I've refactored the solution just a little bit to reduce repetition:

Run It Online

#include <codecvt>
#include <locale>
#include <string>

std::string char16_to_string(const char16_t* s16)
{
    // https://stackoverflow.com/a/7235204/865719
    std::wstring_convert<std::codecvt_utf8_utf16<char16_t>, char16_t> convert;
    return convert.to_bytes(s16);
}

long char16_to_long(const char16_t* s16)
{
    return stol(char16_to_string(s16));
}

int char16_to_int(const char16_t* s16)
{
    return stoi(char16_to_string(s16));
}