Decimal to hexadecimal conversion program not working?? Don't know why? - c++

Question

below is c++ program for decimal to hexadecimal conversion!!
// decimal to hexadecimal conversion
#include <iostream>
#include <math.h>
#include <string>
using namespace std;
string d2h(int n) {
string s, t;
int i = 0;
while (n >= 1) {
t[i] = n % 16;
switch (t[i]) {
case 10:
t[i] = 'A';
break;
case 11:
t[i] = 'B';
break;
case 12:
t[i] = 'C';
break;
case 13:
t[i] = 'D';
break;
case 14:
t[i] = 'E';
break;
case 15:
t[i] = 'F';
break;
default:
break;
}
s[i] = t[i];
n /= 16;
i++;
}
return s;
}
int main() {
int n;
cin >> n;
cout << d2h(n);
return 0;
}
I am getting nothing as output!!
PS C:\Users\anmol\Desktop\c++projectwork> g++ .\dec2hexadec.cpp
PS C:\Users\anmol\Desktop\c++projectwork> ./a
479
PS C:\Users\anmol\Desktop\c++projectwork>
What should i change??

Answer 1

You are not allocating space in s or t for memory. Use s.push_back() instead of s[i].
You'll probably need to reverse the string as well.
t[i] = n % 16; This does not assign the character '0', but rather the number 0. Why don't you just create 16 cases in your switch statement? Or use the ASCII quirk '0' + (n % 16).

Answer 2

// decimal to hexadecimal conversion
#include <iostream>
#include <math.h>
#include <string>
using namespace std;
string d2h(int n) {
string s, t;
string Sign;
int i = 0;
// n is equal to 0? <0 or >0?
if (n == 0){
return "0";
}
if (n < 0){
Sign = "-";
n *= -1;
}
while (n ) {
t.push_back(n % 16) ;
switch (t[i]) {
case 0:
t[i] = '0';
break;
case 1:
t[i] = '1';
break;
case 2:
t[i] = '2';
break;
case 3:
t[i] = '3';
break;
case 4:
t[i] = '4';
break;
case 5:
t[i] = '5';
break;
case 6:
t[i] = '6';
break;
case 7:
t[i] = '7';
break;
case 8:
t[i] = '8';
break;
case 9:
t[i] = '9';
break;
case 10:
t[i] = 'A';
break;
case 11:
t[i] = 'B';
break;
case 12:
t[i] = 'C';
break;
case 13:
t[i] = 'D';
break;
case 14:
t[i] = 'E';
break;
case 15:
t[i] = 'F';
break;
default:
break;
}
s.push_back(t[i]);
n /= 16;
i++;
}
reverse(s.begin(), s.end());
return Sign+s;
}
int main() {
int n;
cin >> n;
cout << d2h(n);
return 0;
}