Help with C++ do...while loop

[JustTooDank]

So I decided to learn something new, and I decided on C++. Been messing around for a couple hours, and I've encountered a problem I can't understand.

I'm am trying to set up a username/password scenario where it loops on the wrong input, and continues on the right input. The username part works fine, but the password part always fails the first time, and succeeds the second time. I can't figure out why it's failing the first time. 

 

Code:

   const char CorrectUser[9]="TestUser";    string username;     do {     cout<<"Username:\n";    cin>> username;    cin.ignore();     if (username==CorrectUser){        cout<<"Password:\n";    }    else {        cout<<"\nIncorrect username. Please try again.\n\n";    }    } while (username!="TestUser");    cin.get();      const char CorrectPass[9]="TestPass";    string thepassword;     do {     cout<<"Password:\n";    cin>> thepassword;    cin.ignore();     if (thepassword==CorrectPass){        cout<<"\nLogging in...\nCorrect!\n";    }    else {        cout<<"Logging in...Incorrect password. Please try again.\n\n";    }    } while (thepassword!="TestPass");    cin.get(); //End of Login Process

[JamieF]

 

So I decided to learn something new, and I decided on C++. Been messing around for a couple hours, and I've encountered a problem I can't understand.

I'm am trying to set up a username/password scenario where it loops on the wrong input, and continues on the right input. The username part works fine, but the password part always fails the first time, and succeeds the second time. I can't figure out why it's failing the first time. 

 

Code:

   const char CorrectUser[9]="TestUser";    string username;     do {     cout<<"Username:\n";    cin>> username;    cin.ignore();     if (username==CorrectUser){        cout<<"Password:\n";    }    else {        cout<<"\nIncorrect username. Please try again.\n\n";    }    } while (username!="TestUser");    cin.get();      const char CorrectPass[9]="TestPass";    string thepassword;     do {     cout<<"Password:\n";    cin>> thepassword;    cin.ignore();     if (thepassword==CorrectPass){        cout<<"\nLogging in...\nCorrect!\n";    }    else {        cout<<"Logging in...Incorrect password. Please try again.\n\n";    }    } while (thepassword!="TestPass");    cin.get(); //End of Login Process

#include <iostream>#include <string>using namespace std;    int main()    {const char CorrectUser[9]="TestUser";    string username;    cout<<"Username:\n";    cin>> username;    cin.ignore();    while (username!="TestUser") {    cout<<"Logging in...Incorrect username. Please try again.\n";    cin >> username;    }    if (username==CorrectUser) {        cout<<"Password:\n";    }    const char CorrectPass[9]="TestPass";    string thepassword;    cin>> thepassword;    cin.ignore();    while (thepassword!="TestPass") {    cout<<"Logging in...Incorrect password. Please try again.\n";    cin >> thepassword;    }    if (thepassword==CorrectPass) {        cout<<"\nLogging in...\nCorrect!\n";    }//End of Login Process}

I used While loops instead of do loops. It works but sorry if it isn't perfect code, i'm learning c++ as well

[JustTooDank]

I used While loops instead of do loops. It works but sorry if it isn't perfect code, i'm learning c++ as well

Thanks a bunch dude.

[Rekhyt]

If you look at the order of instructions in your code, you'll realize you're prompting for the username, then doing cin.get, then cin >> thepassword resulting in strange behavior (if you echo the promted password at that point you'll see it's "estPass", the first character is missing.

 

Here's a better version of that code, using c++ variable assignment, and taking out the unnecessary steps, like repeating "TestUser". The point of variables is to use them everywhere, instead of hard coding what they contain!

#include <iostream>using namespace std;int main(){  const string userName("TestUser");  const string userPass("TestPass");  string inputName;  string inputPass; //Declare variables at the top, using C++ syntax for assignment  cout << "Username: \n"; //Prompt User name once  cin >> inputName;  while(inputName != userName) { //the Whole loop will be ignored if the User name is correct    cout << "Incorrect Username, try again \n Username: \n"; //If not prompt again but with error message    cin >> inputName;  }//Once the first looop is exited or ignored, repeat for the password  cout << "Password: \n";  cin >> inputPass;  while(inputPass != userPass) {    cout << "Incorrect Password, try again \n Username: \n";    cin >> inputPass;  }cout << "Login Succesful.";//End of Login Process}

[LePawel]

Well, considering he's got problems with do..whiles, which are perfect for user input with error detection/verification, why not use them

#include <iostream>using namespace std;int main(){  const string userName("TestUser");  const string userPass("TestPass");  string inputName = "";  string inputPass = ""; //another way of initializing strings  do{     if(inputName != "") //ignored on first pass      cout << "Incorrect Username, try again\n"; //If wrong prompt again but with error message    cout << "Username:\n";     cin >> inputName;  }while(inputName != userName);  do{    if(inputPass != "") //ignored on first pass      cout << "Incorrect Password, try again\n"; //If wrong prompt again but with error message    cout << "Username:\n";    cin >> inputPass;  }while(inputPass != userPass);cout << "Login Succesful.";//End of Login Process}