十进制转换成十六进制的问题

如果是整形转换成16进制比较简单，如果是很大的一个整数呢？  比如 123456789123456789.

参考文章 http://www.cnblogs.com/phinecos/archive/2009/09/11/1564975.html

下面是基于这种思想自己实现的。

#include <iostream>
#include <vector>
#include <string>

#define HEX 16

char s[] = "0123456789ABCDEF"; //字典


//将一个整数转换成十六进制
void dec2hex(int n,std::string& strHex)
{
	std::vector<int> vecRemainder;
	
	int nTemp = n;

	while(nTemp != 0)
	{
		vecRemainder.push_back(nTemp%HEX);
		nTemp /= HEX;
	}

	std::vector<int>::const_iterator itor = vecRemainder.begin();
	for (; itor != vecRemainder.end();itor++)
	{
		strHex.insert(strHex.begin(),1,s[*itor]);
	}
}

//将一个大的十进制转换成十六进制
void dec2hex(std::string strDec,std::string& strHex)
{
	//这一步只是把strDec字符串存到int向量中
	std::string::const_iterator itor_str = strDec.begin();
	std::vector<int> vecDec;
	for (; itor_str != strDec.end(); itor_str++)
	{
		if ( '0' <= (*itor_str) && '9' >= (*itor_str))
		{
			vecDec.push_back(*itor_str - '0');
		}
	}

	//用来保存每一轮的余数
	std::vector<int> vecRemainder;
	while ( vecDec.size() !=0)
	{
		std::vector<int> vecTem=vecDec;
		//vecDec用来保存下一轮的商
		vecDec.clear();

		std::vector<int>::const_iterator itor_temp = vecTem.begin();
		int nTemp = 0;
		bool bStart = true;
		for (;itor_temp != vecTem.end(); itor_temp++)
		{
			nTemp = nTemp*10 + *itor_temp;
			if ( bStart && nTemp/16 <1)
			{
				continue;
			}
			bStart = false;

			vecDec.push_back(nTemp/16);

			if ( nTemp/16 > 0)
			{
				nTemp = nTemp%16;
			}
		}
		vecRemainder.push_back(nTemp);
	}

	std::vector<int>::const_iterator itor = vecRemainder.begin();
	for (; itor != vecRemainder.end();itor++)
	{
		strHex.insert(strHex.begin(),1,s[*itor]);
	}
}

int main()
{
	//std::string strDec = "161";
	std::string strDec = "1234567891234567891";
	std::string strHex;
	dec2hex(strDec,strHex);

	return 0;
}