Thread: Need help for comparing a char to an array char

  1. #1
    Registered User
    Join Date
    Nov 2012

    Need help for comparing a char to an array char

    Im trying to compare a single char to an array of chars like for example

    char input[100];
    char notValid[20] = {'A','B','C'}
    cin << input
    if(char input[0] == notValid) //
    basically here im comparing input[0] for each element in the notValid array. but my code instead checks the first element only in the array. How to compare it to all elements in the notValid array?

  2. #2
    Bored Programmer
    Join Date
    Jul 2009
    Tomball, TX
    Run a for loop and use the loop control variable as the index to the array.

    for(int loopcontrol = 0; loopcontrol < arraysize; loopcontrol++)
      if(input[loopcontrol] == stuff)
        return true;
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  3. #3
    Join Date
    Oct 2007
    Inside my computer
    It is unclear what you are trying to achieve.
    But first off, do not ever mix char arrays and std::cin >>. Use std::string instead of char arrays.
    So, what do you want to accomplish? Do you want to see if your inputted strings consists of one or more of the not valid input characters?
    If so, then this should do what you want:

    std::string input;
    const std::array<char> notValid({'A','B','C'}); // Requires a recent C++11 compiler.
    const char notValid[] = { 'A', 'B', 'C' }; // Use this if the above does not compile
    std::cin >> input;
    if (std::find_first_of(input.begin(), input.end(), notValid.begin(), notValid.end()) != input.end()) // Use if your compiler supports C++11
    if (std::find_first_of( input.begin(), input.end(), notValid, notValid + (sizeof(notValid) / sizeof(notValid[0])) ) != input.end()) // Use if you compiler does NOT support C++11
    	// One or more characters in notValid was found in input.
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    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

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