#include <stdio.h>
#include <stdlib.h>
#include <math.h>
double machine_epsilon(void);
int read_array(const char *name, double *a, unsigned int n);
void print_array(double *a, unsigned int n);
void f(double *a, unsigned int n, double *b, unsigned int m);

double machine_epsilon(void)
{
    double eps = 1;

    while( (1 + eps/2)>1 )
        eps /= 2;

    return eps;
}

/* Ф-ия заменяет каждый элемент массива a на 0, если он совпадает с каким-то элементов в b. */
void f(double *a, unsigned int n, double *b, unsigned int m)
{
    unsigned int i, j;
    double eps = machine_epsilon();

    for( i = 0; i<n; i++ )
        for( j = 0; j<m; j++ )
            if( fabs(a[i] - b[j])<eps )
            {
                a[i] = 0;
                break;
            }
}

void print_array(double *a, unsigned int n)
{
    unsigned int i;

    for( i = 0; i<n; i++ )
        printf("array[%u]==%lf\t", i, a[i]);

    printf("\n");
}

int read_array(const char *name, double *a, unsigned int n)
{
    FILE *input;
    unsigned int i;

    if( !(input = fopen(name, "r")) ) return -1;

    for( i = 0; i<n; i++ )
    {
        if( fscanf(input, "%lf", a + i)!=1  )
        {
            fclose(input);
            return -2;
        }
    }

    fclose(input);
    return 0;
}

int main(int argc, const char *argv[])
{
    unsigned int n, m;
    int res;
    double *a, *b;

    if( (argc!=5) || (sscanf(argv[1], "%u", &n)!=1) || (sscanf(argv[3], "%u", &m)!=1) )
    {
        fprintf(stderr, "Usage: %s [n] [file1] [m] [file2]\n", argv[0]);
        return -1;
    }

    a = (double *)malloc(n*sizeof(double));
    if( !a )
    {
        fprintf(stderr, "Not enough memory!\n");
        return -2;
    }
    b = (double *)malloc(m*sizeof(double));
    if( !b )
    {
        fprintf(stderr, "Not enough memory!\n");
        free(a);
        return -2;
    }

    res = read_array(argv[2], a, n);
    if( res<0 )
    {
        free(a);
        free(b);
        switch(res)
        {
        case -1:
            fprintf(stderr, "Can not open %s\n", argv[2]);
            return 0;
        case -2:
            fprintf(stderr, "Can not read %s\n", argv[2]);
            return 0;
        default:
            fprintf(stderr, "Unknown error %d in %s\n", res, argv[2]);
            return 0;
        }
    }

    res = read_array(argv[4], b, m);
    if( res<0 )
    {
        free(a);
        free(b);
        switch(res)
        {
        case -1:
            fprintf(stderr, "Can not open %s\n", argv[4]);
            return 0;
        case -2:
            fprintf(stderr, "Can not read %s\n", argv[4]);
            return 0;
        default:
            fprintf(stderr, "Unknown error %d in %s\n", res, argv[4]);
            return 0;
        }
    }

    printf("Array a[]:\n");
    print_array(a, n);
    printf("Array b[]:\n");
    print_array(b, m);

    f(a, n, b, m);
    printf("\nf(a, n, b, m) completed!\n\n");

    printf("Array a[]:\n");
    print_array(a, n);
    printf("Array b[]:\n");
    print_array(b, m);

    free(a);
    free(b);
    return 0;
}