String inputs, 1 or 2?

This is a discussion on String inputs, 1 or 2? within the C++ Programming forums, part of the General Programming Boards category; Basically, in the program I'm working on now, there is a point that calls for the user to input a ...

  1. #1
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    String inputs, 1 or 2?

    Basically, in the program I'm working on now, there is a point that calls for the user to input a string. Apparently, the compiler sees
    characters separated by a space as separate strings. In my program there are options for this string input, for example:

    Bardiche
    Earth Render

    Thus far I can only set it to accept one or the other; if I use
    a cin followed by two strings, I can continue with Earth Render
    but if I enter Bardiche the program still demands a second string.
    Likewise, if I use a cin followed by one string the program will only check the input BEFORE the space for the conditions that follow. Any help on how to remedy this issue, so that the program can immediately check the input if it is one string long and if so not force the user to enter a second string?

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    try
    Code:
    cin >> whatever:
    cin.ignore(256,'\n');

  3. #3
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    Have you got any problematic code you can post up so we can help you?

    Anyways, If you mean when you hit a statement like this:

    Code:
    cin >> mystrvar;
    And you enter input like this:

    Code:
    Lee Thomas
    And you try to output mystrvar and you only get this:

    Code:
    Lee
    Then use fgets instead:

    Code:
    fgets (mystrvar.c_str(), 20);
    Actually I'm pretty certain my call to fgets above is incorrect so check with MSDN / man first just to make sure
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    Supermassive black hole cboard_member's Avatar
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    Quote Originally Posted by swanley007
    try
    Code:
    cin >> whatever:
    cin.ignore(256,'\n');
    Damn, beat me
    I've never seen that done before either. Learnt something new.
    Good class architecture is not like a Swiss Army Knife; it should be more like a well balanced throwing knife.

    - Mike McShaffry

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    Ya my code will pull all in until it encounters the enter key being pressed to input and will ignore and not add the return character to the string

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    2 quick ways I see:

    First way:
    For C++ strings use std::getline, for C-strings (arrays) use std::cin.getline
    These will store everything you enter until the user hits the enter-key. Then just check how many spaces there are.

    second way:
    Have the user input one word first, and if the word is Earth, have the user input another word.

    And as a comment to swanleys "solution": That wont help the poster. How in the world does calling cin.ignore going to help him pull out the second string if there exists one?? It will just "delete" it from memory.
    Last edited by Shakti; 10-01-2005 at 02:16 PM.
    STL Util a small headers-only library with various utility functions. Mainly for fun but feedback is welcome.

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    Shakti, if you can post an example as to how to use std::getline, I think that would solve the problem.

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    Registered User hk_mp5kpdw's Avatar
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    Code:
    #include <string>
    
    ...
    
    std::string line;
    
    ...
    
    // store everything up until the first newline character into "line"
    std::getline(std::cin,line);
    "Owners of dogs will have noticed that, if you provide them with food and water and shelter and affection, they will think you are god. Whereas owners of cats are compelled to realize that, if you provide them with food and water and shelter and affection, they draw the conclusion that they are gods."
    -Christopher Hitchens

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    Well......that doens't work......the best I got was

    Code:
    std::getline(cin>>"Earth Render",line)
    cout<<line
    cout<<line showed only " Render"

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    no no no, getline is used instead of std::cin, you use the call exactly as it was showed to you. Here is a completely working program:
    Code:
    #include <iostream>
    #include <string>
    
    int main()
    {
        std::string inputString;
        std::getline(std::cin, inputString);
        std::cout << inputString << std::endl;
        std::cin.get();
    }
    if I input something like "this is just a test to see if everything works", in the console that pops up it will output the same.

    Not to mention that your example doesnt compile.
    Last edited by Shakti; 10-01-2005 at 02:42 PM.
    STL Util a small headers-only library with various utility functions. Mainly for fun but feedback is welcome.

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    Hmm......does for me..."Earth Render" is what I actually enter, mind you.

    In any case, using the code you posted, what happens is that in the
    Code:
    for(;;)
    {
    cout<<"Which weapon?"<<endl;
        for(int i=0;i<5;i++)
        {
        cout<<sWeap[iCount][i]<<endl;
        }
    /////////////////////////
    string sWeapIN;
    getline(cin,sWeapIN);
    cout<<sWeapIN<<endl;
    system("PAUSE");
    /////////////////////////
    This is, of course, not the entire for(; loop but the relevant part of it. The first time the program encounters this snippet, it basically goes straight to the pause...sWeapIN is empty on the output. Once I hit a key, the loop goes back to the beginning and doens't skip the lines the second time.
    Last edited by SkyRaign; 10-01-2005 at 05:07 PM.

  12. #12
    Dae
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    Tried extracting whatevers already in the cin stream? You should be clearing the stream after every time you use cin, but for this case, just try entering cin.ignore(); before the getline(). You could also try cin.clear();, or I believe I got this off Prelude:
    Code:
    #include <limits>
    
    cin.ignore (std::numeric_limits <std::streamsize>::max (), '\n');
    Warning: Have doubt in anything I post.

    GCC 4.5, Boost 1.40, Code::Blocks 8.02, Ubuntu 9.10 010001000110000101100101

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    Your entire code if it's small enough would be helpful to diagnose the problem. It probably requires a call to ignore() to ignore a leftover newline as Dae mentioned, but if the example program provided by Shakti doesn't work it might be a known bug in VC++ 6.0 (if you use that).

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