Decimal to hexadecimal converter

[imnotprogrammer]

Hi everyone. Im trying to make decimal to hexadecimal converter. The code is given below:

 #include<iostream>
#include<cstring>
using namespace std;
void hexadecimal(int x);

int main()
{
	int num;
	cout<<"Enter a number"<<endl;
	cin>>num;
	hexadecimal(num);
	system("pause");
	return 0;
}

void hexadecimal(int x)
{
	int rem, qou;
	string hex[10];
	for(int i=0 ; i<10 ; i++)
		hex[i] = "\n";
	qou = x/16;
	cout<<qou;
	rem = x%16;
	hex[0] = qou;
	for(int i=1 ; i<=rem ; i++)
	{
		qou = x/16;
		rem = x%16;
		hex[i]= qou;

	}
	for(int i=0 ; hex[i] != "\n" ; i++)
	{
		cout<<hex[i]<<endl;
	}

}

i know im doing it wrong. can anyone help me to do it right.And at line 33 and 35 != and << operators are also not working. can anyone here explain???

[abhishekm71]

try this. haven't tested it.

void hexadecimal(int x)
{
  string hex[10];
  int index = 0; // position to insert in hex
  do {
    rem = x%16;
    if (rem > 9) 
      hex[index] = 'A' + rem - 10;
    else
      hex[index] = '0' + rem;
    index++;
    x /= 16;
  } while (x);
  for(int i=index-1 ; i>=0 ; i--)
  {
     cout << hex[i];
  }
  cout << endl;
}

EDIT: Bit operations would be more efficient.
instead of rem = x % 16; you can do rem = x & 15;
instead of x /= 16; you can do x >> 4;

[imnotprogrammer]

at line 16 insertion operator is not working....

[Chervil]

You don't need an array of strings. Use either a single string, or an array of characters.
char hex[10];

[cire]

Two approaches:

#include <iostream>
#include <iomanip>
#include <string>
#include <limits>

std::string as_hex( unsigned value )
{
    const char* digits = "0123456789ABCDEF" ;

    std::string num("0x") ;

    unsigned hexDigits = std::numeric_limits<unsigned>::digits / 4 ;

    unsigned i=0;
    unsigned byteMask = 0xF << (hexDigits-1)*4 ;

    // skip leading 0's
    while ( i < hexDigits && (byteMask & value) == 0 )
    {
        byteMask >>= 4 ;
        ++i ;
    }

    while ( i < hexDigits )
    {
        unsigned digit = (byteMask & value) >> 4*(hexDigits-i-1) ;
        num += digits[digit] ;

        byteMask >>= 4 ;
        ++i ;
    }

    if ( num.length() == 2 )
        num += '0' ;

    return num ;
}

int main()
{
    int num ;

    std::cout << "Enter a number: " ;
    std::cin >> num ;

    std::cout << std::showbase ;
    std::cout << num << " is " << std::hex << num << '\n' ;

    std::cout << std::dec << num << " is " << as_hex(num) << '\n' ; 
}