Hexadecimal to signed decimal

[mike99]

HI,
How to convert a 12 bit hex string into a signed decimal.Is there a direct function to convert a hexadecimal in string to a signed decimal independent of system archi(32 bit or 64 bit), strtol is used but not for negative values.

#include <iostream>
#include <conio.h>
#include <sstream>

using namespace std;
  int _tmain(int argc, _TCHAR* argv[])
{
	unsigned int x[3];
	stringstream ss;
	string A[3]={"ade","0de","fff"};
	ss<<hex<<A<<endl;
	for(int i=0;i<3;i++)
	{
	
	ss>>x[i];
	cout<<x[i]<<"    "<<static_cast<int>(x[i])<<endl;
	}
	_getch();
	return 0;
}

I want the equivalent negative values of the string array.

Thanks in advance

[kevinkjt2000]

My personal favorite thing to use is std::string to do the job.

#include <cctype>
#include <iostream>
#include <string>

int hextoi(std::string hex)
{
    int num = 0;
    int pow16 = 1;
    std::string alpha("0123456789ABCDEF");
    for(int i = hex.length() - 1; i >= 0; --i)
    {
        num += alpha.find(toupper(hex[i])) * pow16;
        pow16 *= 16;
    }
    return num;
}

int main(int argc, char** argv)
{
    std::cout << hextoi("af1") << std::endl;
    std::cout << hextoi("00f") << std::endl;
    std::cout << hextoi("10A") << std::endl;
    std::cout << hextoi("9D") << std::endl;
    return 0;
}