Re: Writing a .txt file

"Lucress Carol" <incognito.me@gmx.de> ha scritto nel messaggio
news:8833fa2d-9693-41d0-b45b-0f6b0fe3561c@d21g2000prf.googlegroups.com...


This is a possible implementation (new comments are identified by // @@ ).
The structure of the code does not change a lot, but using std::vector
instead of raw C++ arrays helps a lot for debugging (e.g. catching array
index out of bounds), etc.

<code>

//////////////////////////////////////////////////////////////////////////

#include <stdlib.h>
#include <time.h>
#include <iostream>
#include <fstream> // @@ Write to file
#include <vector> // @@ vector container

// @@
// I would not include all std namespace, but only classes I need
// using namespace std;

using std::cout;
using std::endl;
using std::ofstream;

// @@ array of doubles
typedef std::vector< double > DoubleArray;

// The function RandomNum creates random numbers
// in the range between small and big
// @@ use DoubleArray
void RandomNum(double small, double big ,int p, DoubleArray & array)
{
    double range=(big-small)+1;

    // @@ I used .at() method to be sure that array indexes
    // are bounds-checked.
    // If you need super-fast performance, you can still
    // use operator[] (not bounds-checked, so less safe,
    // but more fast).

    for (int i=0; i<p; i++){
        array.at(i)=small+int(range*rand()/(RAND_MAX + 1.0));
    }
}

//the function AdditionArr Add the elements of an
//array and store the result in a number S
// @@ use const DoubleArray &, because it is read-only parameter
double AdditionArr (const DoubleArray & Arr,int k)
{
    int i;
    double Sum=0.0;
    for (i=0; i<k; i++){
        Sum+=Arr.at(i);
    }
    return Sum;
}

int main()
{
    srand((unsigned)time(0));
    int p=3;
    int j;
    double S;

    // @@ a robust std::vector
    DoubleArray array(3);

    // *** Create output file
    ofstream outFile;
    outFile.open( "I:\\OutFile.txt" );

    // @@ code modified to use DoubleArray
    for(j=0;j<3;j++){
        RandomNum(-1.5,1.5 ,p,array);

        S = AdditionArr(array, p);
        for (int k=0; k<p; k++){
            cout << "array"<<"["<< k << "]" <<" = " << array.at(k) << endl;
        }
        cout << "S=" << S << endl;

        // *** Write to file
        outFile << "j=" << j << " S=" << S << endl;

        cout << endl;
    }

    // *** Closes the file
    // (The destructor does that, too)
    outFile.close();

    return 0;
}

//////////////////////////////////////////////////////////////////////////

</code>

Giovanni