C++ : Converting String into an array of Char - c++

Question

I've managed to convert an array of char into a string but now I want to do the other way around, I tried using strcpy in my code but it doesn't seem to give me what I want. The expected result should be 5, I'm getting 40959 as a result
#include <iostream>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#include <algorithm>
using namespace std;
string DecToBin(int);
int BinToDec(string);
int main()
{
int x = 5;
string y = DecToBin(x);
reverse(y.begin(), y.end());
int z = BinToDec(y);
cout << z << endl;
}
string DecToBin(int num)
{
char res[16];
for (int n = 15; n >= 0; n--)
{
if ((num - pow(2, n)) >= 0)
{
res[n] = '1';
num -= pow(2, n);
}
else
{
res[n] = '0';
}
}
for (int n = 15; n >= 0; n--)
{
res[n];
}
return res;
}
int BinToDec(string num)
{
char x[16];
strcpy(x, num.c_str());
int res;
for (int n = 15; n >= 0; n--)
{
if (x[n] == '1')
{
res += pow(2, n);
}
}
return res;
}

Answer 1

I can find the following errors:
res is not zero-terminated in DecToBin before it is copied into the string,
res is not initialized in BinToDec,
You reverse the binary representation but try to read it back in the same way you wrote it.
This looks to me like homework, so I leave fixing the code to you. In the event that you really need this productively for something, an easier way to achieve this (that will not be accepted as homework anywhere) is
#include <iostream>
#include <bitset>
#include <string>
using namespace std;
string DecToBin(int num) {
std::bitset<16> b(num);
return b.to_string();
}
int BinToDec(string num) {
std::bitset<16> b(num);
return static_cast<int>(b.to_ulong());
}