Problems with Looping

I have a c++ problem regarding looping. I am writing a program which will include a problem similar to below.

1) ok, i am writing a program that asks the user to enter a number.

2) Then ask the user if the number entered was correct.

3) If the number is correct, the user will enter 'y' or 'yes' and the program will terminate.
(pretty simple so far ?

4) If the user enters 'n' or 'no' the program should loop back to the beginning of the program and start again. goes back to 1)

5) However, if the user enters anything other than 'yes' or 'no', the program rejects this input and tells the user to re-enter, using only 'yes' or 'no'.

6) This should be asked infinitely until either 'yes' or 'no' is inputted, after which the program then loops back to the beginning.
how would i do this ?

i've been trying do while and switch but no luck. would i have to use a for loop ?

Thanks

If you've been trying to do this "for a while, " then you've got some code that shows that and some errors and/or problems you'd like to address. Let's see both/all of those.

Quote:

---

Originally Posted by rags_to_riches

If you've been trying to do this "for a while, " then you've got some code that shows that and some errors and/or problems you'd like to address. Let's see both/all of those.

---

Code:

---

#include <iostream.h>
#include <string>
#include <conio.h>

main()
{
        string date;
  char answer; //either yes or no
  bool check;

do        {
                cout << "\nplease enter the date in dd/mm/yyyy: "; //beginning of loop********************************
      cin >> date;

      cout << "\nIs this the correct date ? press y/n \n" << date << "\n\n";
      cin >> answer;

      switch (answer) {
              case 'y':
                cout << "\nThank you!!\n";
            break;

      }while (answer != 'y');
  }  getch();
}

---

ok then, if u insist.
here we go then.

There isn't such a thing as a switch-while loop. Perhaps you want a switch inside of a loop.

Quote:

---

Originally Posted by tabstop

There isn't such a thing as a switch-while loop. Perhaps you want a switch inside of a loop.

---

how would you go about writing what i am trying to do ?

And now upon rereading I see that very lonely do up there at the top. So the loop appears to be fine -- the question now is: what do you want to do? Do you only want to give a message when they type 'y'? What if they type 'n'? What if they type 'q'? The requirements state you need yet another loop to handle the case of weird input.

There's no closing '}' on the switch block.

You could use a while loop and get rid of the switch, just use an if statement.

BTW my compiler does not like <iostream.h>

Code:

---

#include <iostream.h>
#include <string>
#include <conio.h>

main()
{
        string date;
  char answer; //either yes or no
  bool check;

do        {  //beginning of loop********************************
                cout << "\nplease enter the date in dd/mm/yyyy: ";
      cin >> date;

      cout << "\nIs this the correct date ? press y/n \n" << date << "\n\n";
      cin >> answer;

      switch (answer) {
              case 'y':
                cout << "\nThank you!!\n";
            break;

      }
        }while (answer != 'y');
}

---

here is what i ended up with

i'm sure an if statement wouldnt loop though

The if would replace the switch. Inside the loop.

Does your program work now?

Quote:

---

Originally Posted by fadlan12

Does your program work now?

---

you mean,

Code:

---

#include <iostream.h>
#include <string>
#include <conio.h>

main()
{
        string date;
  char answer; //either yes or no
  bool check;

do        {  //beginning of loop********************************
                cout << "\nplease enter the date in dd/mm/yyyy: ";
      cin >> date;

      cout << "\nIs this the correct date ? press y/n \n" << date << "\n\n";
      cin >> answer;

      if (answer = 'y')
      cout << "\nThank you!!\n";
      break;


        }while (answer != 'y');
}

---

it wont loop with the if

Can you get it to compile without my suggestion? It won't compile for me at all with your code. I got it to work with a while loop and an if statement inside. But your code is missing a few things, for ex when you compile it says string, cin, cout etc not declared.

= is for assignment, == for comparison

I wrote the program and it works perfectly, but there's a catch.

Code:

---

#include <iostream.h>
#include <string>
using namespace std;

int main()
{
        string date;
  char answer; //either yes or no
  bool check;

  do{cout << "\nplease enter the date in dd/mm/yyyy: "; cin >> date; cout << "\nIs this the correct date ? press y/n \n" << date << "\n\n";  cin >> answer; if (answer == 'y'){ cout << "\nThank you!!\n"; break; } else if (answer != 'n' && answer != 'y') { cout << "invalid input\n"; } } while (answer == 'n' && answer != 'n' || answer != 'y'); system ("pause"); return 0;
}

---

i got it to loop and put it in my program, (right at the end. last 7 lines)...

but, i have a problem. When a non integer is inputted, the program crashes.
how do i get around this ?

Code:

---

#include <iostream.h>
#include <string>
#include <conio.h>
main()
{
int salescode, bikeprice, modelcode, quantity;
  string date;
  char answer; //either yes or no


  do
        //the instructions to enter the i.d. code will be repeated (do...while
        //loop) as long as the salescode is less than 1 or greater than 20.
          {

              cout << "\n\nPlease enter your identifiction code ";
        cin >> salescode;

        //the condition is tested
        if (salescode < 1 || salescode > 20)

                {
                    cout << ("\nTHIS I.D. CODE IS NOT VALID. TRY AGAIN \n");
            }
      }
        //the instructions to enter the i.d. code will be repeated (do...while
  //loop) as long as the salescode is less than 1 or greater than 20.
  while (1 > salescode || salescode > 20);

  //another do...while loop
  do
          {
              cout << "\nPlease enter the bike price (one unit = 1 Euro) ";
              cin >> bikeprice;

        if (bikeprice < 1 || bikeprice > 500)

                {
                    cout << ("\nINVALID PRICE. Bike prices cannot be 0 or more than 500. TRY AGAIN \n");
            }
      }

  while (bikeprice < 1 || bikeprice > 500);

  //another do...while loop
  do
          {
              cout << "\nPlease enter the 3 digit model code ";
              cin >> modelcode;

        if (modelcode < 0 || modelcode > 999)

                {
                    cout << ("\nINVALID MODEL CODE. TRY AGAIN \n");
            }
      }

  while (modelcode < 0 || modelcode > 999);

  //another do...while loop
  do
          {
        cout << ("\nPlease enter the quantity sold ");
              cin >> quantity;

        if (quantity < 1 || quantity > 10)

        {
                cout << ("\nINVALID QUANTITY. TRY A NUMBER FROM 1-10 \n");
        }
      }

  while (quantity < 1 || quantity > 10);

        do {


                        cout << "\nPlease enter the date in this format dd/mm/yyyy: ";
        cin >> date;

                        cout << "\nIs this the correct date ?\t" << date << "\tpress y/n: \n\n";
        cin >> answer;  //gets answer from user

                        switch (answer)        {
                case 'y':
                    cout << "\n\n\nThank You!\n\n";
              break;
            }
        }while (answer != 'y');
  }

---

Shouldn't those be AND operators? saying OR means that only on side has to be true for it to continue.

Quote:

---

Originally Posted by fadlan12

Shouldn't those be AND operators? saying OR means that only on side has to be true for it to continue.

---

nope, does not work.
a number cannot be smaller than 1 AND bigger than 10

As to the actual question you asked, have you read the FAQ yet, particularly Cprogramming.com FAQ > Convert a string to a int (C++) ?

Quote:

---

Originally Posted by tabstop

As to the actual question you asked, have you read the FAQ yet, particularly Cprogramming.com FAQ > Convert a string to a int (C++) ?

---

the thing is, my compiler does not recognize the language.
Unfortunately, we HAVE to use borland c++ 5.02 !
Any idea how to stop the program from crashing when a non character is inputted ? - in regards to my program preceding this reply ?
thanks

Which part doesn't it recognize?

You can't use >> by definition since that will not read in a character.

Quote:

---

Originally Posted by tabstop

Which part doesn't it recognize?

You can't use >> by definition since that will not read in a character.

---

Info :Compiling E:\program\noname00.cpp
Error: noname00.cpp(1,2):Unable to open include file 'SSTREAM.h' ??????????????
Warn : STRING.h(549,3):Functions containing for are not expanded inline
Warn : STRING.h(557,3):Functions containing while are not expanded inline
Warn : STRING.h(563,3):Functions containing for are not expanded inline
Warn : STRING.h(575,3):Functions containing for are not expanded inline
Warn : string.cc(686,32):Comparing signed and unsigned values
Error: noname00.cpp(37,25):Undefined symbol 'istringstream' ??????????
Error: noname00.cpp(37,25):Statement missing ; ?????????????
Error: noname00.cpp(39,17):Undefined symbol 'myStream' ???????
Warn : noname00.cpp(43,2):Parameter 's' is never used
Warn : noname00.cpp(43,2):Parameter 'i' is never used

are you trying to accomplish something like this

Code:

---

#include <string>
#include <iostream>
#include "input.h" //function prototype of double readDouble(string prompt, bool allowNegatives)
using namespace std;

int main()
{
  double month;//use whatever u want here
  double day;
  double year;
  char resp;
  char no='n';
    yes='y';
  do{
      double month=readDouble("Enter a month ",false);
      double day=readDouble("Enter a day ",false);
      double cin>>year=readDouble("Enter a year ",false);
      cout<<"Is this date correct "<<month<<"/"<<day<<"/"<<year<<endl;
      cin>>resp;
  }while(resp=='n'||resp==no);
  //while(resp=='y'||resp==yes)
  //put whatever u want here
}

double readDouble(string prompt, bool allowNegatives)
{
        double rv=0.0;
        bool done=false;
        do
        {
        cout<<prompt;
        cin>>rv;
        while(cin.fail()!=0)
        {
                cerr<<"Cannot read data!"<<endl;
                cin.clear();
                cin.ignore(256,'\n');
                cout<<prompt;
                cin>>rv;
                }
        if (allowNegatives==false && rv<0)
        {
                cerr<<"Input positive numbers!"<<endl;
                cin.clear();
                cin.ignore(256,'\n');
                cin>>rv;
                }
        else
        {
        done=true;
        }

        return rv;
        }
        while(done==false);
}

---

breakup code however needed,
now that im looking at this the char no='n' and char yes='y' are not needed