/**输入大于4位的用户名，输出注册码 
*/
#include<iostream>
#include<string>
#include<math.h>
using namespace std;

//input the string when the length <5 exit
void check(string t)
{
    if(t.length()<5)
    {
        cout<<"your name must longer than four";
        exit(0);
    }
    
}


//input the string  reverse orde it 
void sort(string& a)
{
    char temp;
    int size=a.length();
//    cout<<size/2<<endl;
    int i=0;
    while(i<size/2)
    {
        temp=a[size-1-i];
        a[size-1-i]=a[i];
        a[i]=temp;
        i++;
    }
}


//xor every char of two string in common length
//the result in string a

void charxor(string& a,string& b)
{
    int i=0;
    while(i<a.length()||i<b.length())
    {
        a[i]^=b[i];
        i++;
    }
}



//input string print hex of if 
//for the reason of oxffffff00 so have a choice
void printstr_hex(string a)
{
    int pwd;
    int i=0,j=7;
    while(i<4)
        {
            if(a[i]>=0xffffff00)
            {
                pwd+=(a[i]&0x000000ff)/16*pow(16,j);
                j--;
                pwd+=(a[i]&0x000000ff)%16*pow(16,j);
                j--;
            }
            else
            {
                pwd+=a[i]/16*pow(16,j);
                j--;
                pwd+=(a[i]%16)*pow(16,j);
                j--;
            }
            i++;
        }
        cout<<pwd; 
}

//xor input and 5DFEE4A4 per 4 chars
void stringxor(string& a)
{
    string x="\x5D\xFE\xE4\xA4";
    string y;
    for(int i=0;i<a.length()-4;i++)
    {
        y.assign(a,i,4);
        sort(y);          //y为倒序取出的4个字符 
        charxor(x,y);
    }
    printstr_hex(x);   
}

int main()
{
    string a;
    cout<<"input your reg name \n";
    cin>>a;
    check(a);               //check the number of input char
    stringxor(a);
    system("pause");
}

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