代码来源：舍友大一的C++作业
【代码存在的问题】
在菜单界面选择对应序号时，若输入值非数字，而是字母等其它符号，会导致程序陷入循环，无法正常进入功能的下一步
原代码展示：
int main()
{
system("color 8E");
int k,i,choose,orderflag=1;
double t_sum;
book* head = new book;
trolley* head2 = new trolley;
layfolk* l_head = new layfolk;
member* m_head = new member;
honoured_guest* h_head = new honoured_guest;
historyorder* o_head = new historyorder;
head->Loaddata(head);
l_head->loaddata(l_head);
m_head->loaddata(m_head);
h_head->loaddata(h_head);
string ch;
while (1)
{
system("color 8E");
system("cls");
printf("\n\n\n");
printf("\t\t\t\t+-----------TouhouBookStore-----------+\n");
printf("\t\t\t\t|--------------东方铃奈庵-------------|\n");
printf("\t\t\t\t+-------------网上购书系统------------+\n");
printf("\t\t\t\t+-------------------------------------+\n");
printf("\t\t\t\t|\t1 查看历史订单\t\t |\n");
printf("\t\t\t\t|\t2 查看个人会员信息\t |\n");
printf("\t\t\t\t|\t3 查看店内书籍\t\t |\n");
printf("\t\t\t\t|\t4 搜索店内书籍\t\t |\n");
printf("\t\t\t\t|\t5 购买书籍\t\t |\n");
printf("\t\t\t\t|\t6 结算\t\t\t |\n");
printf("\t\t\t\t|\t7 退出\t\t\t |\n");
printf("\t\t\t\t+-------------------------------------+\n");
printf("\n\n\n");
printf("\t\t\t\t请输入你想实现的功能前的代号：\n");
printf("\t\t\t\t");
cin >> k;
switch(k)
{
case 1:
{
cout<<"您的身份是："<<endl;
cout<<"1)会员\t2)贵宾\t3)普通顾客"<<endl;
cin>>choose;
switch(choose)
{
case 1:
{
o_head->m_display(head2,m_head);break;
}
case 2:
{
o_head->h_display(head2,h_head);break;
}
case 3:
{
o_head->l_display(head2,l_head);break;
}
default:break;
}
break;
}
case 2:
{
system("cls");
cout<<"\n请选择您的会员身份：\n"<<endl;
cout<<"1.我是会员\t2.我是贵宾\t3.我是普通顾客\n\n";
cout<<"请输入对应的身份序号：";
cin>>k;
while(!k)
{
cin.clear();
cin.sync();
k=-1;
break;
}
system("cls");
if(k==1)
{ m_head->find(m_head);system("pause"); }
else if(k==2)
{ h_head->find(h_head);system("pause"); }
else if(k==3)
{ l_head->find(l_head);system("pause"); }
else
{
cout<<"请输入正确的序号！"<<endl;system("pause"); }
break;
}
case 3: system("cls");head->display(head);system("pause");break;
case 4:
{
cout<<"请选择搜索方式："<<"\n\n";
cout<<"1.按照书名搜索\t2.按照作者名字搜索\t3.按关键字搜索"<<"\n\n";
cout<<"请输入你想要选择的方式序号：";
cin>>k;
while(!k)
{
cin.clear();
cin.sync();
k=-1;
break;
}
system("cls");
if(k==1)
{ head->find_name(head);system("pause"); }
else if(k==2)
{ head->find_author(head);system("pause"); }
else if(k==3)
{ head->find_critical(head);system("pause"); }
else
{
cout<<"请输入正确的序号！"<<endl;system("pause"); }
break;
}
case 5: head2->Addbook(head2,head);system("pause");break;
case 6:
{
t_sum=head2->count(head2);
if(t_sum==-1)
{
system("pause");
break;
}
cout<<"您的身份是："<<endl;
cout<<"1)会员\t2)贵宾\t3)普通顾客"<<endl;
cin>>choose;
switch(choose)
{
case 1:
{
orderflag=o_head->m_storage(head2,m_head,t_sum);
if(orderflag!=-1)
{
cout<<"请进行下一步支付步骤"<<"\n\n";
system("pause");
head2->pay();
head2->remake(head2);
}
break;
}
case 2:
{
orderflag=o_head->h_storage(head2,h_head,t_sum);
if(orderflag!=-1)
{
cout<<"请进行下一步支付步骤"<<"\n\n";
system("pause");
head2->pay();
head2->remake(head2);
}
break;
}
case 3:
{
orderflag=o_head->l_storage(head2,l_head,t_sum);
if(orderflag!=-1)
{
cout<<"请进行下一步支付步骤"<<"\n\n";
system("pause");
head2->pay();
head2->remake(head2);
}
break;
}
default:break;
}
break;
}
case 7: head->Savedata(head);return 0;
case 8: head->Addbook(head);break;
case 9:
{
system("cls");
cout<<"\n请选择要进行添加的顾客信息：\n\n";
cout<<"1.添加新会员\t2.添加新贵宾\t3.添加普通顾客信息\n\n";
cout<<"请输入对应序号：";
cin>>k;
while(!k)
{
cin.clear();
cin.sync();
k=-1;
break;
}
system("cls");
if(k==1)
{ m_head->addm(m_head);m_head->savedata(m_head);system("pause"); }
else if(k==2)
{ h_head->addh(h_head);h_head->savedata(h_head);system("pause"); }
else if(k==3)
{ l_head->addl(l_head);l_head->savedata(l_head);system("pause"); }
else
{cout<<"请输入正确的序号！"<<endl;system("pause"); }
break;
}
default:
{
cout<<"请输入正确序号！"<<endl;
system("pause");
break;
}
}
}
return 0;
}
【问题产生的原因】
由于接收数值的变量k为int类型，在接收字母或其它字符等char类型时，导致程序出现问题
【解决方案】
应用cin.clear()更改cin的异常状态标识，再用cin.sync()函数对缓冲区中的数据流进行清理，然后给变量k赋值为-1，进入switch选择后将跳转至default一列，随后结束此次循环。后续代码运行将恢复正常。
//将这几行代码嵌入至给变量k赋值的 cin>>k; 之后即可
while(!k)
{
cin.clear();
cin.sync();
k=-1;
break;
}
【修改后的代码】
int main()
{
system("color 8E");
int k,i,choose,orderflag=1;
double t_sum;
book* head = new book;
trolley* head2 = new trolley;
layfolk* l_head = new layfolk;
member* m_head = new member;
honoured_guest* h_head = new honoured_guest;
historyorder* o_head = new historyorder;
head->Loaddata(head);
l_head->loaddata(l_head);
m_head->loaddata(m_head);
h_head->loaddata(h_head);
string ch;
while (1)
{
system("color 8E");
system("cls");
printf("\n\n\n");
printf("\t\t\t\t+-----------TouhouBookStore-----------+\n");
printf("\t\t\t\t|--------------东方铃奈庵-------------|\n");
printf("\t\t\t\t+-------------网上购书系统------------+\n");
printf("\t\t\t\t+-------------------------------------+\n");
printf("\t\t\t\t|\t1 查看历史订单\t\t |\n");
printf("\t\t\t\t|\t2 查看个人会员信息\t |\n");
printf("\t\t\t\t|\t3 查看店内书籍\t\t |\n");
printf("\t\t\t\t|\t4 搜索店内书籍\t\t |\n");
printf("\t\t\t\t|\t5 购买书籍\t\t |\n");
printf("\t\t\t\t|\t6 结算\t\t\t |\n");
printf("\t\t\t\t|\t7 退出\t\t\t |\n");
printf("\t\t\t\t+-------------------------------------+\n");
printf("\n\n\n");
printf("\t\t\t\t请输入你想实现的功能前的代号：\n");
printf("\t\t\t\t");
cin >> k;
while(!k) {
cin.clear();
cin.sync();
k=-1; break;
}
switch(k)
{
case 1:
{
cout<<"您的身份是："<<endl;
cout<<"1)会员\t2)贵宾\t3)普通顾客"<<endl;
cin>>choose;
switch(choose)
{
case 1:
{
o_head->m_display(head2,m_head);break;
}
case 2:
{
o_head->h_display(head2,h_head);break;
}
case 3:
{
o_head->l_display(head2,l_head);break;
}
default:break;
}
break;
}
case 2:
{
system("cls");
cout<<"\n请选择您的会员身份：\n"<<endl;
cout<<"1.我是会员\t2.我是贵宾\t3.我是普通顾客\n\n";
cout<<"请输入对应的身份序号：";
cin>>k;
while(!k)
{
cin.clear();
cin.sync();
k=-1;
break;
}
system("cls");
if(k==1)
{ m_head->find(m_head);system("pause"); }
else if(k==2)
{ h_head->find(h_head);system("pause"); }
else if(k==3)
{ l_head->find(l_head);system("pause"); }
else
{
cout<<"请输入正确的序号！"<<endl;system("pause"); }
break;
}
case 3: system("cls");head->display(head);system("pause");break;
case 4:
{
cout<<"请选择搜索方式："<<"\n\n";
cout<<"1.按照书名搜索\t2.按照作者名字搜索\t3.按关键字搜索"<<"\n\n";
cout<<"请输入你想要选择的方式序号：";
cin>>k;
while(!k)
{
cin.clear();
cin.sync();
k=-1;
break;
}
system("cls");
if(k==1)
{ head->find_name(head);system("pause"); }
else if(k==2)
{ head->find_author(head);system("pause"); }
else if(k==3)
{ head->find_critical(head);system("pause"); }
else
{
cout<<"请输入正确的序号！"<<endl;system("pause"); }
break;
}
case 5: head2->Addbook(head2,head);system("pause");break;
case 6:
{
t_sum=head2->count(head2);
if(t_sum==-1)
{
system("pause");
break;
}
cout<<"您的身份是："<<endl;
cout<<"1)会员\t2)贵宾\t3)普通顾客"<<endl;
cin>>choose;
switch(choose)
{
case 1:
{
orderflag=o_head->m_storage(head2,m_head,t_sum);
if(orderflag!=-1)
{
cout<<"请进行下一步支付步骤"<<"\n\n";
system("pause");
head2->pay();
head2->remake(head2);
}
break;
}
case 2:
{
orderflag=o_head->h_storage(head2,h_head,t_sum);
if(orderflag!=-1)
{
cout<<"请进行下一步支付步骤"<<"\n\n";
system("pause");
head2->pay();
head2->remake(head2);
}
break;
}
case 3:
{
orderflag=o_head->l_storage(head2,l_head,t_sum);
if(orderflag!=-1)
{
cout<<"请进行下一步支付步骤"<<"\n\n";
system("pause");
head2->pay();
head2->remake(head2);
}
break;
}
default:break;
}
break;
}
case 7: head->Savedata(head);return 0;
case 8: head->Addbook(head);break;
case 9:
{
system("cls");
cout<<"\n请选择要进行添加的顾客信息：\n\n";
cout<<"1.添加新会员\t2.添加新贵宾\t3.添加普通顾客信息\n\n";
cout<<"请输入对应序号：";
cin>>k;
while(!k)
{
cin.clear();
cin.sync();
k=-1;
break;
}
system("cls");
if(k==1)
{ m_head->addm(m_head);m_head->savedata(m_head);system("pause"); }
else if(k==2)
{ h_head->addh(h_head);h_head->savedata(h_head);system("pause"); }
else if(k==3)
{ l_head->addl(l_head);l_head->savedata(l_head);system("pause"); }
else
{cout<<"请输入正确的序号！"<<endl;system("pause"); }
break;
}
default:
{
cout<<"请输入正确序号！"<<endl;
system("pause");
break;
}
}
}
return 0;
}
【二次开发所添加的功能】
在功能5购买书籍中，用户在使用的过程体验并不佳，因为无法直观看到自己已经选中了哪些书籍，故在此添加一个“购物车”形式的展示功能
【代码实现】
void trolley::display(trolley* t)
{
if (t->next == NULL)
{
cout << "目前购物车内无信息！\t\t" << endl;
cout << "—————————————————————————————————————————————————————————\n";
}
else
{
cout << "\n您的购物车中目前有以下书籍：" << endl;
cout << "—————————————————————————————————————————————————————————\n";
t = t->next;
int n = 1;
while (1)
{
cout << "NO." << n << ":" << '\t' << endl;
cout << "—————————————————————————————————————————————————————————\n";
cout << "书号：" << t->book_ID << '\t';
cout << "书名：《" << t->book_name << "》" << '\t';
cout << "作者：" << t->author << '\t';
cout << "出版社：" << t->publishing << '\t';
cout << "定价：" << t->price << '\t';
cout << "购买份数:" << t->num << endl;
cout << "—————————————————————————————————————————————————————————\n";
if (t->next == NULL)
break;
else
{
t = t->next;
n++;
}
}
}
}
void trolley::Addbook(trolley* t, book* m)
{
trolley* hd = t;
book* hd2 = m;
trolley* p;
trolley* p1;
string t_name, ch;
int n=0, flag = 0;
while (1)
{
system("cls");
flag = 0;
t->display(hd);
cout << "\n是否继续添加书籍？\n";
cout << "Y)继续添加\tN）返回主菜单\tD)删除订单" << endl;
cin >> ch;
if (ch == "Y" || ch == "y");
else if (ch == "N" || ch == "n")return;
else if (ch == "D" || ch == "d")
{
hd->Delete_t(hd);
system("pause");
continue;
}
else {
cout << "请输入正确指令" << endl; system("pause"); continue;
}
while (t->next != NULL)
{
t = t->next;
}
p = new trolley;
t->next = p;
p->next = NULL;
cout << "请输入想购买的书名：" << endl;
cin >> t_name;
m = hd2;
while (1)
{
if (m->book_name == t_name)
{
++n;
cout << "NO." << n << ":" << '\t' << endl;
cout << "—————————————————————————————————————————————————————————\n";
cout << "书号：" << m->book_ID << '\t';
cout << "书名：《" << m->book_name << "》" << '\t';
cout << "作者：" << m->author << '\t';
cout << "出版社：" << m->publishing << '\t';
cout << "定价：" << m->price << '\n';
cout << "—————————————————————————————————————————————————————————\n\n";
cout << "请问是否确认购买该书籍？" << "\n\n";
cout << "1)Y\t2)N" << "\n\n";
cin >> ch;
if (ch == "N" || ch == "n")
{
t->next = t->next->next;
}
if (ch == "Y" || ch == "y")
{
cout << "请输入您想要购买的份数：";
cin >> n;
p1 = hd;
while (p1 != t)
{
if (p1->next->book_name == t_name)
{
p1->next->num += n;
t->next = t->next->next;
flag = 1;
break;
}
p1 = p1->next;
}
if (flag == 1)break;
p->book_ID = m->book_ID;
p->book_name = t_name;
p->author = m->author;
p->publishing = m->publishing;
p->price = m->price;
p->num = n;
t = p;
}
}
if (m->next == NULL && n == 0)
{
cout << "没有名为《" << t_name << "》的书籍" << endl;
break;
}
if (m->next == NULL)
{
break;
}
m = m->next;
}
cout << "是否继续购买？" << endl;
cout << "Y)继续购买\tN）返回主菜单" << endl;
cin >> ch;
if (ch == "Y" || ch == "y");
if (ch == "N" || ch == "n")break;
}
}
如此一来，用户便能够清楚地看到自己所购买的书籍内容了
标签：case,head,购书,head2,system,C++,break,测试,printf From： https://www.cnblogs.com/marisa514/p/17196194.html