C语言，进制转换之二进制转十六进制，完整代码

#include "iostream"using namespace std;#define MAX 50int _2to16()//二转十六{    cout << "请输入二进制数，并以‘$’结束：";     char elem2[MAX];    int flag = 1;    char ch;    int i = 0;    while (flag)    {        cin >> ch;        if (ch != '$')        {            elem2[i] = ch;            i++;        }        else        {            flag = 0;        }    }    int length = i;    int n = 0;    int sum = 0;    int product = 0;    if (length % 4 != 0)//将缺位的二进制码用0补齐    {        int n = 4 - length % 4;        int i = 0;        for (i = length - 1; i >= 0; i--)            elem2[i + n] = elem2[i];        length += n;        for (i = 0; i < n; i++)            elem2[i] = '0';        cout << "补齐之后的内容是：" << endl;        for (i = 0; i < length; i++)            cout << elem2[i]<<" ";        cout << endl;    }    for (n = 0; n < length; n++)//判断是否是二进制数    {        if ('1' == elem2[n] || '0' == elem2[n])            sum++;    }    if (sum == length)    {        char elem16[MAX];        int r = 0;        int m = 0;        int p = 0;        int q = 0;        for (m = length - 1; m >= 0; m--)        {            q = elem2[m] - '0';            product += q * pow(2, p);            p++;            if (4 == p)            {                if (product>9)                elem16[r] = product+55;//输出A...F范围                else                {                    elem16[r] = product+48;//输出0...9范围                }                r++;                p = 0;                product = 0;            }        }        int j = 0;        cout << "对应的十六进制数是：OX";        for (j = r - 1; j >= 0; j--)            cout << elem16[j];        cout << endl;    }    else    {        cout << "你输入的不是二进制数！" << endl;    }    return 0;}