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  1. #1
    Join Date
    Apr 2013

    Read from file

    I want my program to read variables from file "input.txt":
    Please choose the crystal lattice. Type 1 for BCC, 2 for FCC, and 3 for HCP: 2
    Please enter lattice parameter (a): 1
    For HCP please enter second lattice parameter (c): 1
    Please enter the number of translated cells along X axis: 2
    Please enter the number of translated cells along Y axis: 2
    Please enter the number of translated cells along Z axis: 2
    Moreover, I want program to read only the numbers after colon. How can I do it?
    #include <iostream>#include <fstream> // to read from file
    using namespace std;
    int main ()
        int latticeType;
        int dimX, dimY, dimZ; // number of translated cells along each axis
        float d; // lattice parameter
        float h; // second lattice parameter for HCP
        ifstream inputFile; // object of class 'ifstream' to read from it
        inputFile.open("input.txt", ios::in); // open 'input.txt' only for reading
        if (!inputFile){
            cerr << "Unable to open input file";
            return -1;
        while (!inputFile.eof()){
            inputFile >> latticeType;
            cout << latticeType << endl;
        if ( (latticeType!=1) && (latticeType!=2) && (latticeType!=3) ){
            cerr << "Invalid value of lattice type" << endl;
            return -1;
            inputFile >> d;
            cout << d << endl;
            if (latticeType==3){
                inputFile >> h;
                cout << d << endl;
            inputFile >> dimX;
            cout << dimX;
            inputFile >> dimY;
            cout << dimY;
            inputFile >> dimZ;
            cout << dimZ;
        return 0;
    Last edited by ted_kingdom; May 12th, 2013 at 01:26 PM.

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