cin.ignore()

This is a discussion on cin.ignore() within the C++ Programming forums, part of the General Programming Boards category; Hey guys I was sitting on Efnet irc and this kid came in saying that he needed to use cin.ignore() ...

  1. #1
    Sweet
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    cin.ignore()

    Hey guys I was sitting on Efnet irc and this kid came in saying that he needed to use cin.ignore() to block input after the first letter on a string(for a school assignment). I was just wondering if this is possible(it intriges(sp) me) and if so how would you go about it.
    Woop?

  2. #2
    i dont know Vicious's Avatar
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    Hmm, seems like you would need to ignore it after its been typed..

    odd..

    It intrigues(sp) me also.
    What is C++?

  3. #3
    unleashed alphaoide's Avatar
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    http://cplusplus.com/ref/iostream/istream/ignore.html
    Code:
    // istream ignore
    #include <iostream>
    using namespace std;
    
    int main () {
      char first, last;
    
      cout << "Enter your first and last names: ";
    
      first=cin.get();
      cin.ignore(256,' ');
    
      last=cin.get();
    
      cout << "Your initials are " << first << last;
    
      return 0;
    }
    source: compsci textbooks, cboard.cprogramming.com, world wide web, common sense

  4. #4
    Registered User stillwell's Avatar
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    If I wanted to have the option to have 3 names, how would I make it skip the last name, if the person has only 2 names?

    I tried to make it like this, but it only works where there are 3 names.
    Code:
    int d = 0;
    char a, b, c;
    
    while (d == 0)
    {
    cout << "Inset your name ";
    
    a = cin.get();
    cin.ignore(30, ' ');
    b = cin.get();
    cin.ignore(30, ' ');
    c = cin.get();
    
    cout << endl << "Your intials are: " << a << "." << b << "."<< c << ".\n\n";
    Last edited by stillwell; 10-04-2004 at 02:13 PM.

  5. #5
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    explicitly ask the user if they want to enter a first name/last name/other name, and if the answer is yes, then get their input, otherwise, move on. Alternatively, input the name as a single string and parse the string into the first name/middle name/last name/honorary name/etc" based on spaces between the "names".

  6. #6
    Banned master5001's Avatar
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    I would actually keep your as is, but then check to see if c is a newline character. If c is a '\n' then they only have two names.

  7. #7
    Banned master5001's Avatar
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    By the way, are you certain that you need to make multiple calls to ignore() like that?

  8. #8
    Registered User stillwell's Avatar
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    I'm pretty new to programming, so I have no idea if I need to do it like this.

    I have a new problem. Now it works with 2 names, but not 3

    Here is the code
    Code:
    main()
    {
    int d = 0;
    char a, b, c;
    
    while (d == 0)
    {
    cout << "Inset your name ";
    
    a = cin.get();
    cin.ignore(30, ' ');
    b = cin.get();
    if (!(c = '\n'))
    {
    cin.ignore(30, ' ');
    c = cin.get();
    }
    
    cout << endl << "Your intials are: " << a << "." << b;
    
    if  (!(c = '\n'))
    cout << "."<< c << ".\n\n";
    else
    cout << ".\n\n";
    }
            return 0;
    }
    And how do I clear the char variables, when it returns in the while loop?
    Last edited by stillwell; 10-04-2004 at 02:45 PM.

  9. #9
    Banned master5001's Avatar
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    Kinda, but no. Plus you don't need the infinite loop. Additionally, I was playing with it, ignore() is the most retardedly useless function ever.

    Code:
    #include <iostream>
    
    int main(void) {
      bool done = false;
      char a, b, c;
    
      while(!done) {
        std::cout << "Inset your name ";
    
        a = cin.get();
        std::cin.ignore(30, ' ');
        b = std::cin.get();
        std::cin.ignore(30, ' ');
        c = cin.get();
    
        if(c == '\n')
          std::cout << std::endl << "Your intials are: " << a << "." << b << std::endl;
        else
          std::cout << std::endl << "Your intials are: " << a << "." << b << "."<< c << std::endl;
    
        std::cout << "continue?";
        done = (std::cin.get() == 'y')?false:true;
      }
    
      return 0;
    }

  10. #10
    Banned master5001's Avatar
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    Ah hah! I've learned when something seems useless, you are using it wrong.

    http://www.augustcouncil.com/~tgibso...al/iotips.html

    For those interested how to use ignore().

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