UDL for converting ints into std::strings and char * (online link http://cpp.sh/8bju7)

intstrUDL.cpp

#include <deque> // if you use vectors instead you have to add them to the string in reverse order (no push_front())
#include <string>
#include <iostream> // for testing types
#include <cxxabi.h> // ditto
#include <typeinfo> // also for testing types
char * Demangle(const char* Object)
{
    int status;
    char * RealName;
    
    RealName = abi::__cxa_demangle(Object, 0 , 0, &status);
    return RealName;
}
std::string operator"" _str(unsigned long long int num)
{
    std::deque<char> digits;
    for(char i = 0; num != 0;num = num / 10)
    {
        i = '0'+(num % 10);
        digits.push_front(i);
        
    }
    std::string converternum;
    for(auto i = 0; i< digits.size();i++)
      converternum += digits[i];
    return converternum;
}
char * operator"" _cstr(unsigned long long int num)
{
    std::deque<char> digits;
    for(char i = 0; num != 0;num = num / 10)
    {
        i = '0'+(num % 10);
        digits.push_front(i);
        
    }
    std::string converternum;
    for(auto i = 0; i< digits.size();i++)
      converternum += digits[i];
      char * string = (char *)converternum.c_str();
    return string;//converternum.c_str();
}
    
int main()
{
  auto cstr = 213_cstr;
  auto str = 213_str;
  std::cout << Demangle(typeid(str).name()) << std::endl << Demangle(typeid(cstr).name()) << std::endl;
  
  return 0;
}