FileIO2.c

#include<stdio.h>
#include<stdlib.h> //exit()

int main()
{
    FILE* fpl;
    FILE* fpw;
    FILE* fpa;

    float l[20] ;
    float w[20];
    float a[20];

    int fstatus = 0; // 0 - neutral
    float data = 0.0;
    int index = 0;
    int lcount = 0;
    int wcount = 0;

    for (int k = 0; k < 20; k++)
    {
        l[k] = -1;
        w[k] = -1;
        a[k] = -1;
    }


    //1-read l values and store in l array
    fopen_s(&fpl, "I:\\test\\l.txt", "r");
    if (fpl == NULL)
    {
        printf("!Error, cannot open file!");
        exit(1);
    }
    do {
        fstatus = fscanf_s(fpl, "%f", &data); //success = 1 , fail = -1
        if (fstatus == 1)//1 - OK | -1 Not OK
        {
            l[index] = data;
            index++;
        }
    } while (fstatus != -1);
    lcount = index;
    fclose(fpl);

    //2-read w values and store in w array
    index = 0;
    fopen_s(&fpw, "I:\\test\\w.txt", "r");
    if (fpw == NULL)
    {
        printf("!Error, cannot open file!");
        exit(1);
    }
    do {
        fstatus = fscanf_s(fpw, "%f", &data); //success = 1 , fail = -1
        if (fstatus == 1)//1 - OK | -1 Not OK
        {
            w[index] = data;
            index++;
        }
    } while (fstatus != -1);
    wcount = index;
    fclose(fpw);

    //3-calculate area and store in a.txt file
    if (lcount == wcount)
    {
        for (int j = 0; j < lcount; j++)
        {
            a[j] = l[j] * w[j];
        }
    }
    fopen_s(&fpa, "I:\\test\\a.txt", "w");
    if (fpa == NULL)
    {
        printf("!Error, cannot open file!");
        exit(1);
    }
    for (int z = 0; z < lcount; z++)
    {
        fprintf_s(fpa, "%0.2f\n", a[z]);
    }
    fclose(fpa); //really save to file in harddisk
    return 0;
}