Number System in C++ - c++

Question

I have a program that should translate values ​​from one number system to another, but I have a problem with "_itoa_s" writes that [Error] '_itoa_s' was not declared in this scope I tried to connect libraries <cstdlib> and <stdlib.h> I also tried replacing itoa with "snprintf" but it does not help in the compiler there are even more errors, please help me fix the error,
Here is the code:
#include <cstring>
#include <iostream>
#include <cmath>
using namespace std;
int main()
{
setlocale(LC_ALL, "rus");
int in, iz, k, s = 0, p;
char str[255];
cout << "Enter the number system from which you want to translate" << endl;
cin >> iz;
cout << "Enter the number system to which we will translate" << endl;
cin >> in;
cout << "Enter the number" << endl;
cin >> str;
p = strlen(str) - 1;
for (int i = 0; i < str[i]; i++)
{
switch (str[i])
{
case 'a': k = 10; break;
case 'b': k = 11; break;
case 'c': k = 12; break;
case 'd': k = 13; break;
case 'e': k = 14; break;
case 'f': k = 15; break;
case '1': k = 1; break;
case '2': k = 2; break;
case '3': k = 3; break;
case '4': k = 4; break;
case '5': k = 5; break;
case '6': k = 6; break;
case '7': k = 7; break;
case '8': k = 8; break;
case '9': k = 9; break;
case '0': k = 0; break;
}
s = s + k * pow(iz, p);
p--;
}
char result[255];
_itoa_s(s, result, in);
cout << "The result of a translation from a radix " << iz << " to radix " << in << " = " << result;
return 0;
}

Answer 1

Here's an alternative that doesn't involve switch, pow or itoa:
// Notice, the index is the value of the digit.
const std::string digits[] = "0123456789abcdef";
//...
const size_t length = str.len;
// Note: iz is the radix for "input" conversion
int number = 0;
for (unsigned int i = 0; i < length; ++i)
{
const std::string::size_type position = digits.find(str[i]);
number = number * iz; // Shift the number by one digit.
number += position;
}
Notice: error handling, such as invalid digits, is left as an exercise for the OP. Invalid digits are not restricted to characters outside the set, but also digits whose index is greater than the conversion radix.
For ultimate understanding, single step through the code with pen and paper. :-)
You can use the table for converting to the target radix, in (I'd rather use a more descriptive variable name).
std::string translated_number;
while (number > 0)
{
const unsigned int index = number % output_radix; // Output_radix == 'in'
const char digit_character = digits[index];
translated_number.insert(0, 1, digit_character);
number = number / output_radix;
}