Issue when validating input where a negative number prints the invalid message twice

[thorny solstice]

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[soft raven]

Oh here's the console output in both scenarios:

Select a medium:
a) Air
b) Water
c) Steel
Enter your choice (a/b/c): 3
Invalid choice. Please enter a, b, or c:```

a) Air
b) Water
c) Steel
Enter your choice (a/b/c): -3
Invalid choice. Please enter a, b, or c: Invalid choice. Please enter a, b, or c:```

[thorny solstice]

@soft raven

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[soft raven]

#include <iomanip>
using namespace std;

int main() {
    // Set speeds
    const double airSpeed = 1100;
    const double waterSpeed = 4900;
    const double steelSpeed = 16400;

    char choice;
    double distance, time;

    // Display menu of materials
    cout << "Select a medium:\n"
         << "a) Air\n"
         << "b) Water\n"
         << "c) Steel\n"
         << "Enter your choice (a/b/c): ";
    cin >> choice;

    // Validate user input
    while (choice != 'a' && choice != 'b' && choice != 'c') {
        cout << "Invalid choice. Please enter a, b, or c: ";
        cin >> choice;
    }

    // Get distance from the user
    cout << "Enter the distance a sound wave will travel in the selected medium (in feet): ";
    cin >> distance;

    // Validate distance
    while (distance < 0) {
        cout << "Distance cannot be less than 0. Please enter a valid distance: ";
        cin >> distance;
    }

    // Calculate time
    time = distance / airSpeed;

    // Change output depending on material
    if (choice == 'a') {
        cout << "A sound wave takes " << fixed << setprecision(4) << time
             << " seconds to travel " << distance << " feet through air.\n";
    } else if (choice == 'b') {
        cout << "A sound wave takes " << fixed << setprecision(4) << time
             << " seconds to travel " << distance << " feet through water.\n";
    } else if (choice == 'c') {
        cout << "A sound wave takes " << fixed << setprecision(4) << time
             << " seconds to travel " << distance << " feet through steel.\n";
    }

    return 0;
}```
Fixed this code by adding cin.ignore();

#include <iomanip>
using namespace std;

int main() {
    // Set speeds
    const double airSpeed = 1100;
    const double waterSpeed = 4900;
    const double steelSpeed = 16400;

    char choice;
    double distance, time;

    // Display menu of materials
    cout << "Select a medium:\n"
         << "a) Air\n"
         << "b) Water\n"
         << "c) Steel\n"
         << "Enter your choice (a/b/c): ";
    cin >> choice;

    // Validate user input
    while (choice != 'a' && choice != 'b' && choice != 'c') {
        cout << "Invalid choice. Please enter a, b, or c: ";
        cin.ignore();
        cin >> choice;
    }

    // Get distance from the user
    cout << "Enter the distance a sound wave will travel in the selected medium (in feet): ";
    cin >> distance;

    // Validate distance
    while (distance < 0) {
        cout << "Distance cannot be less than 0. Please enter a valid distance: ";
        cin >> distance;
    }

    // Calculate time
    time = distance / airSpeed;

    // Change output depending on material
    if (choice == 'a') {
        cout << "A sound wave takes " << fixed << setprecision(4) << time
             << " seconds to travel " << distance << " feet through air.\n";
    } else if (choice == 'b') {
        cout << "A sound wave takes " << fixed << setprecision(4) << time
             << " seconds to travel " << distance << " feet through water.\n";
    } else if (choice == 'c') {
        cout << "A sound wave takes " << fixed << setprecision(4) << time
             << " seconds to travel " << distance << " feet through steel.\n";
    }

    return 0;
}```

!solved