Reading Data

This is a discussion on Reading Data within the C++ Programming forums, part of the General Programming Boards category; I need to read a data file that has the following structure name number number number number number I think ...

  1. #1
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    Reading Data

    I need to read a data file that has the following structure

    name number number number number number

    I think I understand how the struct thing works. However all the examples that I have seen deal with a structure like this

    words
    words
    words
    numbers
    numbers

    I just can't figure out how I can extract the name and all the numbers into seperate variables in the code to later be processed.

    Any ideas?

  2. #2
    C++ Witch laserlight's Avatar
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    I just can't figure out how I can extract the name and all the numbers into seperate variables in the code to later be processed.
    Use formatted input, e.g. cin >> x;
    If the name is just a word, x would then be a string, then for the numbers it would be some numeric type like int.
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    The data is coming from a .dat file. I dont know how many lines there are to read from.
    The in would do the same thing wouldn't? Would it skip over the spaces and move to the number after the name? Also what would happen when it got to the end of the line?

  4. #4
    C++ Witch laserlight's Avatar
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    I dont know how many lines there are to read from.
    Use a vector.

    The in would do the same thing wouldn't? Would it skip over the spaces and move to the number after the name?
    If this 'in' that you speak of is a std::istream, yes.

    Also what would happen when it got to the end of the line?
    Iterate over the next line. You know the exact format, after all.
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    I'm still relatively new to C++ so could you explain what you mean using a vector?

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    Screw vectors - manage your own memory and make a function that dynamically resizes an array and use that.

    I don't believe in using all the standard template library crapola until you understand alot of the friggin' language.

    Telling someone to 'use a vector' when they barely know what a struct is can't be a good idea and I can't stand people who make such suggestions.

    It's like learning to speak a language but not knowing the any of the grammar.

  7. #7
    C++ Witch laserlight's Avatar
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    I'm still relatively new to C++ so could you explain what you mean using a vector?
    At the moment, dont think about reading all the lines. First, how would you read in a single line into your struct?

    I don't believe in using all the standard template library crapola until you understand alot of the friggin' language.

    Telling someone to 'use a vector' when they barely know what a struct is can't be a good idea and I can't stand people who make such suggestions.
    Go read Accelerated C++: Practical Programming by Example by Andrew Koenig and Barbara E. Moo
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    Basically, a vector is a container that can store multiple values. Think of it as a resizable array; it automatially resizes itself whenever needed eg. when you add an element.

    One important feature is that you can create a vector to hold elements of any type you like; int, double or even your own structs/classes. It's simply a *container*, an empty shell to store other objects.

    Example:

    Code:
    #include <vector>
    
    //like cout, vector is part of std
    using namespace std;
    
    int main()
    {
        //our vector will be named X, and will hold values of type int
        vector <int> X;
        //our second one holds doubles
        vector <double> Y;
        
        //add an element to vector; resizing is done automatically
        X.push_back(1);
        int n = 123;
        X.push_back(n);
        
        n = some_function();
        X.push_back(some_function());
        
        
        //now retrieve values
        //basic way would be to use size() in the vector
        for(int i = 0; i < X.size(); ++i)
        {
            cout << "Element #" << i << " is " << X[i] << "\n";
        }
    }
    Hope that helps. There are lots of stuff about vectors and other similiar standard C++ library containers out there on the net, just Google around.
    Code:
    #include <stdio.h>
    
    void J(char*a){int f,i=0,c='1';for(;a[i]!='0';++i)if(i==81){
    puts(a);return;}for(;c<='9';++c){for(f=0;f<9;++f)if(a[i-i%27+i%9
    /3*3+f/3*9+f%3]==c||a[i%9+f*9]==c||a[i-i%9+f]==c)goto e;a[i]=c;J(a);a[i]
    ='0';e:;}}int main(int c,char**v){int t=0;if(c>1){for(;v[1][
    t];++t);if(t==81){J(v[1]);return 0;}}puts("sudoku [0-9]{81}");return 1;}

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