C ++使用cin執行while循環

Question

下面是我用cin做while while循環有點問題，當用戶輸入Fullname然后按回車鍵。 指針將轉到下一行。 直到用戶再次按回車鍵，然后它會提示電子郵件地址，如何在我的代碼輸入全名后立即提示電子郵件地址

終端外觀：

Full Name: John
Email Address: some_email@gmail.com

我的test.cpp代碼：

emailAddress= "";
fullname = "";
counter = 0;

if(department_selection!="")
{

while(fullname=="")
{
if(counter>0)
{
//so it wont print twice
cout << "Full Name: ";
}

getline(cin,fullname);
cin.clear();
cin.ignore();
counter++;
}

counter = 0;

while(emailAddress=="")
{
if(counter>0)
{
//so it wont print twice
cout << "Email Address: ";
}

getline(cin,emailAddress);
cin.clear();
cin.ignore();
counter++;
}

}// if department selection not blank

還是同樣的問題。 我需要輸入一次，然后提示輸入電子郵件地址。

最新更新：管理以修復它。 我對代碼進行了更改，它是這個版本：

do
{
  if(counter==0)
  {
     //so it wont print twice
     cout << "Full Name: ";
  }
  if(counter>1)
  {
     //so it wont print twice
     cout << "Full Name: ";
  }

  getline(cin,fullname);
  counter++;
} while (fullname=="");

counter = 0;

do
{
  if(counter==0)
  {
     //so it wont print twice
     cout << "Email Address: ";
  }
  if(counter>1)
    {
         cout << "Email Address: ";
    }

  getline(cin,emailAddress);
  counter++;
} while (emailAddress=="");

Answer 1

而不是if(counter>0)使用if(counter==0)

我的工作測試應用：

int counter = 0;
string fullname, emailAddress;
do
{
  if(counter==0)
  {
     //so it wont print twice
     cout << "Full Name: ";
  }

  getline(cin,fullname);
  counter++;
} while (fullname=="");

counter = 0;

do
{
  if(counter==0)
  {
     //so it wont print twice
     cout << "Email Address: ";
  }

  getline(cin,emailAddress);
  counter++;
} while (emailAddress=="");

Answer 2

檢查長度，然后檢查@。

 do
    {
    ...
    }while(fullname.length()<2);

    do
    {
    ...
    }while(emailAddress.length()<3||emailAddress.find("@")==string::npos);

Answer 3

使用clear（）和ignore（）函數也可以忽略已存儲在輸入中的單詞

Answer 4

定義一個函數以避免重復代碼：

#include <iostream>
#include <string>
#include <limits>

using namespace std;

string get_input(const std::string& prompt)
{
    string temp;
    cout << prompt;
    while (!getline(cin, temp) || temp.empty()) {
        cin.clear();
        cin.ignore(numeric_limits<streamsize>::max(), '\n');
    }
    return temp;
}

int main()
{
    string fullname = get_input("Full Name: ");
    string email = get_input("Email Adress: ");
}