C++——循环的经典应用

#include  <iostream>
#include  <Windows.h>
#include <string>
using namespace std;
int main (void){
       string pwd;
       while (1) {
              cout << "Please input your password: ";
              cin >> pwd;
              if (pwd == "000123") {
                     break;
              } else {
                     cout << "Password error." << endl;
              }
       }
       cout << "login success" << endl;
       cout << "1. 注册" << endl;
       cout << "2. 管理" << endl;
       cout << "3. 查询" << endl;
       cout << "4. 删除" << endl;
       system("pause");
       return 0;
}

#include <iostream>
using namespace std;
int main(void) {
         char pwd[7];
         char dict[64]; //10+26+26+1 = 63；
         char tmp[32];
         int index = 0;
         for (int i=0; i<10; i++) {
                  dict[index++] = '0' + i;
         }
         /*
         for (int i=0; i<26; i++) {
                  dict[index++] = 'a' + i;
         }
         for (int i=0; i<26; i++) {
                  dict[index++] = 'A' + i;
         }
         dict[index++] = '_';
         */
         dict[index] = '\0';
         int n = index; // 字符个数
         for (int p1=0; p1<n; p1++) {
                  for (int p2=0; p2<n; p2++) {
                           for (int p3=0; p3<n; p3++) {
                                    for(int p4=0; p4<n; p4++) {
                                             for(int p5=0; p5<n; p5++){
                                                      for (int p6=0; p6<n; p6++) {
                                                               tmp[0] = dict[p1];
                                                               tmp[1] = dict[p2];
                                                               tmp[2] = dict[p3];
                                                               tmp[3] = dict[p4];
                                                               tmp[4] = dict[p5];
                                                               tmp[5] = dict[p6];
                                                               tmp[6] = '\0';
                                                               cout << tmp << endl;
                                                      }
                                             }
                                    }
                           }
                  }
         }
         return 0;
}