• toHexString(int n) 函数，输入整型数字n，返回 字符串string类。

#include <iostream>
#include <string>
#include <vector>
#include <math.h>
using namespace std;

string toHexString(int n)
{
    vector <int> v;
    char m[15] = { '1' ,'2' ,'3' ,'4' ,'5' ,'6' ,'7' ,'8' ,'9' ,'A' ,'B' ,'C' ,'D' ,'E' ,'F' };
    int  over = 0;
    for (int j = 1; over == 0; ++j)
    {
        int temp1 = (int)(n / pow(16, j));
        if (temp1 == 0)  over = 1;
        int temp2 = n - temp1 * pow(16, j);
        int l = 0;
        vector <int>::iterator k;
        for (k = v.begin(); k != v.end(); k++)
        {
            temp2 = temp2 - (*k) * pow(16, l);
            l++;
        }
        temp2 = temp2 / pow(16, j - 1);
        v.push_back(temp2);
    }
    int length = v.size();
    char* s = new char[length + 1];
    for (int i = 0; i < length; ++i)
        s[i] = m[v[length - 1 - i] - 1];
    s[length] = '\0';
    string mys = s;

    return mys;
}

int main()
{
    int n;
    cin >> n;

    string hexStr = toHexString(n);
    cout << hexStr << endl;

    return 0;
}