File input

This is a discussion on File input within the C++ Programming forums, part of the General Programming Boards category; I get input from a file called "accounts.txt" and try to compare it with a predefined word such as 'blue'. ...

  1. #1
    Registered User
    Join Date
    Oct 2004
    Posts
    12

    File input

    I get input from a file called "accounts.txt" and try to compare it with a predefined word such as 'blue'. Here's an example:

    int main()
    {
    char word[50];
    ifstream file;
    file.open("accounts.txt");
    file>>word;
    if(word == "blue")
    cout<<"The program works";
    else
    cout<<"The program does not work";
    return 0;
    }
    I never get "The program works" even if the only possible word is blue!
    Help me!!!!!!!

  2. #2
    Registered User major_small's Avatar
    Join Date
    May 2003
    Posts
    2,787
    it's because you can't compare C-style strings like that... try:

    Code:
    int main()
    {
    char word[50];
    ifstream file;
    file.open("accounts.txt");
    file>>word;
    if(!strcmpi(word,"blue"))
    cout<<"The program works";
    else
    cout<<"The program does not work";
    return 0;
    }
    by the way: use code tags and format your code...
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  3. #3
    Registered User hk_mp5kpdw's Avatar
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    If you used a std::string instead it would have worked:

    Code:
    #include <iostream>
    #include <string>
    #include <fstream>
    
    int main()
    {
        std::string word;
        std::ifstream file;
        file.open("accounts.txt");
        file >> word;
        if(word == "blue")
            std::cout << "The program works";
        else
            std::cout << "The program does not work";
        return 0;
    }
    The reason it doesn't work for character arrays is that the character string "blue" is a string literal and its use in your comparison statement in effect is trying to compare the address of the character array word with the address of that string literal in memory. Those two addresses will NEVER be the same.
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