CODEWITHSUNDEEP
c++
Zaher
Zaher

Reputation: 1

About the do-while statment with switch

#include <iostream>
using namespace std;

int main() {

    cout << "1. Facebook" << endl;
    cout << "2. Twitter" << endl;
    cout << "3. Instagram" << endl;
    cout << "4. SnapChat" << endl;

    int input;

    do {
        cout << "Enter a selection > ";
        cin >> input;
        switch(input) {
        case 1:
            cout << "Facebook is Loading..." << endl;
            break;
        case 2:
            cout << "Twitter is Loading..." << endl;
        case 3:
            cout << "Instagram is Loading..." << endl;
        case 4:
            cout << "SnapChat is Loading..." << endl;
            break;
        default:
            cout << "Wrong Selection" << endl;
        }
    }while(input =! 1 && input =! 2 && input != 3 && input != 4);
    return 0;
}

I want to retry the progress if I got the wrong selection and I got confused and dunno what to do, so can someone tell me what I should do so I can make it?

Upvotes: 0

Views: 46

Answers (3)

Tony Delroy
Tony Delroy

Reputation: 106226

Firstly...

input =! 1 && input =! 2 && input != 3 && input != 4

... those =! should be !=.

Secondly, if someone types non-numeric input, cin >> input will fail and all future input attempts will instantly fail - without even waiting for the user to type anything further. You need to clear the error state and ignore any bad input characters remaining in the stream - say up to the end of the line:

default:
    cout << "Wrong Selection" << endl;
    std::cin.clear(); // clear error state
    std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');.

You'll need to #include <limits> atop your program to use std::numeric_limts<>.

Separately, you're first two case statements lack a break and will fall through to execute the following case(s) code....

I'd recommend explicitly checking cin >> input for success too, though with C++11 it guarantees to set input to 0 on failure so it will work reliably. With C++03 there's no such guarantee and you may get arbitrary garbage left in input after a failure, which might coincidentally match one of the cases. To handle this explicitly:

if (!(cin >> input)) input = -1; // sentinel meaning erroneous

Upvotes: 1

Ayushi Jha
Ayushi Jha

Reputation: 4023

Add a break statement after each case:

case 2:
cout << "Twitter is Loading..." << endl;
break; 
case 3:
cout << "Instagram is Loading..." << endl;
break;

Change =! to !=

while(input != 1 && input != 2 && input != 3 && input != 4);

Upvotes: 0

ChajusSaib
ChajusSaib

Reputation: 167

You need to make sure you add your breaks after each case if you want the switch statement to break/exit. Else everything underneath is going to be executed. Also you mixed up the != (does not equal) and wrote =!

#include <iostream>
using namespace std;

int main()
{

    cout << "1. Facebook" << endl;
    cout << "2. Twitter" << endl;
    cout << "3. Instagram" << endl;
    cout << "4. SnapChat" << endl;

    int input;

    do {
        cout << "Enter a selection > ";
        cin >> input;
        switch(input) {
        case 1:
            cout << "Facebook is Loading..." << endl;
            break;  
        case 2:
            cout << "Twitter is Loading..." << endl;
            break;  // add break
        case 3:
            cout << "Instagram is Loading..." << endl;
            break;  // add break
        case 4:
            cout << "SnapChat is Loading..." << endl;
            break;  // add break
        default:
            cout << "Wrong Selection" << endl;
        }
    } while(input != 1 && input != 2 && input != 3 && input != 4); // != not =!

    return 0;
}

Upvotes: 0

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