too many chars in my switch print menu too many times

[Jjajangmyeon]

When a user enters multiple keystrokes the meny prints multiple times. It should spit out an error and reprint the menu once...what gives?

void mainMenu(char entries[], int index[])
{
    char choice;
    cout << "Please choose 1, 2, or 3.\n";
    cout << "1. Save a new password\n";
    cout << "2. Display all passwords\n";
    cout << "3. Exit\n\n";
    cout << "Choose 1, 2, or 3: ";
    cin.get(choice);

    while(choice != '1' && choice != '2' && choice != '3')
    {
        cout << "** Invalid Entry **\n";
        cout << "Please choose 1, 2, or 3.\n";
        cout << "1. Save a new password\n";
        cout << "2. Display all passwords\n";
        cout << "3. Exit\n\n";
        cout << "Choose 1, 2, or 3: ";
        cin.get(choice);
    }

    switch(choice)
    {
        case '1': newEntry(entries, index);
        break;
        case '2': display();
        break;
        case '3': exit();
        break;
        default: cout << "\nInvalid Entry\n";
    }
}

[ddanbe]

Why not just use cin >> choice?
And while you 're at it, put lines 4 to 8 in a function and reuse it in your while statement.

[Aspacid]

After the first cin.get(), with an input of 4<enter> you have 4<newline> in the input stream. You get the 4 out of it, but the newline is still there. Since the stream isn't empty your program won't wait for input on the second cin, and read newline instead.

[David W]

This demo of a menu -> choice pattern is simple and easily adapted to many student type menu -> choice problems.

Note how it simply avoids the very common ...

beginning student problem

of 'dangling char's left in the cin stream' :

// showMenuTakeInChoice.cpp //

#include <iostream>
#include <string>
// #include <cctype> //re. tolower


const std::string MENU =
    "1. Save a new password\n"
    "2. Display all passwords\n"
    "3. Exit\n\n"
    "Choose 1, 2, or 3: ";

char takeInChr( const std::string& msg )
{
    std::cout << msg << std::flush;
    std::string reply;
    getline( std::cin, reply );
    if( reply.size() )
        return reply[0];
    // else ...
    return 0;
}

/*
bool more()
{
    if( tolower( takeInChr( "\nMore (y/n) ? " )) == 'n' )
        return false;
    // else ...
    return true;
}
*/


int main()
{
    char choice;
    bool quit = false;
    while( !quit )
    {
        switch( (choice = takeInChr( MENU )) )
        {
            case '1':
                std::cout << "\n'1' is under construction"
                          << " ...\n\n";
            break;
            case '2':
                std::cout << "\n'2' is under construction "
                          << " ...\n\n";
            break;
            case '3':
                quit = true;
                takeInChr( "\nPress 'Enter' to "
                           "continue/EXIT ..." );
            break;
            default:
                std::cout << "\n'" << choice
                          << "' is NOT a valid choice "
                          << "here ...\n\n";
        }
    }
}

[David W]

This demo of a menu -> choice pattern is simple and easily adapted to many student type menu -> choice type problems.

Note how it simply avoids the very common ...

beginning student problem

of 'dangling char's left in the cin stream' :

// showMenuTakeInChoice.cpp //

#include <iostream>
#include <string>


const std::string MENU =
    "1. Save a new password\n"
    "2. Display all passwords\n"
    "3. Exit\n\n"
    "Choose 1, 2, or 3: ";

char takeInChr( const std::string& msg )
{
    std::cout << msg << std::flush;
    std::string reply;
    getline( std::cin, reply );
    if( reply.size() )
        return reply[0];
    // else ...
    return 0;
}

/*
bool more()
{
    if( tolower( takeInChr( "\nMore (y/n) ? " )) == 'n' )
        return false;
    // else ...
    return true;
}
*/


int main()
{
    char choice;
    bool quit = false;
    while( !quit )
    {
        switch( (choice = takeInChr( MENU )) )
        {
            case '1':
                std::cout << "\n'1' is under construction"
                          << " ...\n\n";
            break;
            case '2':
                std::cout << "\n'2' is under construction "
                          << " ...\n\n";
            break;
            case '3':
                quit = true;
                takeInChr( "\nPress 'Enter' to "
                           "continue/EXIT ..." );
            break;
            default:
                std::cout << "\n'" << choice
                          << "' is NOT a valid choice "
                          << "here ...\n\n";
        }
    }
}

[Jjajangmyeon]

Thanks guys, great explanation, and suggestions!