Using swtich cases in conditions

[new programer]

Hello all,

I have been trying to use swtich cases in conditions but it won't work

what I mean is like this;

do{
cout<<"Enter a valid number";
cin>>number;

switch(number)
{
case 0: bla bla
break;
case 1: bla bla
break;
case default: cout<<"re-enter";
}
}while(defalut);

if that can never happen .. what is a good effcient way of accomplishing the same task

Thanks in advance

[necrolin]

It works just fine:

#include <iostream>

using std::cout;
using std::cin;

int main()
{
    bool again = true;

    do
    {
        cout << "Enter a digit between 0 & 1: ";
        int i;
        cin >> i;

        switch (i)
        {
            case (0):
               cout << "You chose 0\n";
               again = false;
               break;
            case (1):
                cout << "You chose 1\n";
                again = false;
                break;
            default:
              cout << "Wrong choice...\n";
        };
    } while (again);

    return 0;
}

[Lilal]

Hey,

You're declaring default wrong, and just need to use an overall boolean while.

int number;
bool valid = false;
do{
cout<<"Enter a valid number ";
cin >> number;

switch(number)
{
case 0: 
	cout << "0 \n";
	valid = true;
	break;
case 1: 
	cout << "1 \n";
	valid = true;
	break;
default: 
	cout << "You Fail \n";
	valid = false;
	break;
}
}while(valid == false);

Should work for any number (Chars will break it, but as you didn't say anything, assuming only numbers)

Thanks Lilly

ps. Oops looks like I was beaten while typing >.<

[Fbody]

You can't use an actual case statement from a switch as a conditional. The cases are linked to the switch structure. You will need to use some other value or a flag of some sort.

bool validInput;

do{
  validInput = true;   //assume input is valid until invalid input detected
  cout<<"Enter a valid number";
  cin>>number;

  switch(number)
  {
    case 0:
      /* ... bla bla; ... */
      break;
    case 1:
      /* ... bla bla; ... */
      break;
    default:
      cout<<"re-enter";
      validInput = false;
  }
} while(!validInput);

ouch, double ninja'd

[new programer]

Thank you both.. that's an excellent way

now regarding char as Lilal pointed out.. is an issue it self

I did a do.. while loop it works just fine when entering a number but it does and infinate loop if the input was a charcter .. how can I over come this?

[Lilal]

Thank you both.. that's an excellent way

now regarding char as Lilal pointed out.. is an issue it self

I did a do.. while loop it works just fine when entering a number but it does and infinate loop if the input was a charcter .. how can I over come this?

Take it in as a string not int, Do an "if isDigit" then cast to int, else ignore it. :P Funs.

Lilly

[new programer]

thank you too Fbody for the explanation..

can you contribute to the solving of the infinate loop issue "when using charcters" in the do.. while

[new programer]

Take it in as a string not int, Do an "if isDigit" then cast to int, else ignore it

okay I got the part about taking it as a string but how do i make sure it is a digit to avoid casting a digit again ..
and by ignoring what do you exactly mean

cheers
:)