Multimi - examen PC

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int cmp(const void *a,const void *b)
{
    return *(int *)a-*(int *)b;
}

int main(int argc, char **argv)
{
    int *A=NULL,*B=NULL,*R,*I,m=0,n=0,k=0,i,a,b,*poz,numar;
    //A=(int *)malloc(m*sizeof(int));
    FILE *f;
    f=fopen("multA.txt","rt");
    while(!feof(f)) //punctele a) si b)
        {
            fscanf(f,"%d",&a);
            A=(int *)realloc(A,(m+1)*sizeof(int));
            if (m!=0)
                {
                    qsort(A,m,sizeof(int),cmp);
                    poz=(int *)bsearch(&a,A,m,sizeof(int),cmp);
                    if (!(poz>0))
                        {
                            A[m]=a;
                            m++;
                        }
                }
            else
                {
                    A[m]=a;
                    m++;
                }
        } //Multimea A va avea m elemente
    qsort(A,m,sizeof(int),cmp);
    fclose(f);
    printf("Multimea A: ");
    for(i=0;i<m;i++)
        printf("%d ",A[i]);
    printf("\n");
    //B=(int *)malloc(n*sizeof(int));
    FILE *g;
    g=fopen("multB.txt","rt");
    while(!feof(f)) //punctele c) si d)
        {
            fscanf(f,"%d",&b);
            B=(int *)realloc(B,(n+1)*sizeof(int));
            if (n!=0)
                {
                    qsort(B,n,sizeof(int),cmp);
                    poz=(int *)bsearch(&b,B,n,sizeof(int),cmp);
                    if (!(poz>0))
                        {
                            B[n]=b;
                            n++;
                        }
                }
            else
                {
                    B[n]=b;
                    n++;
                }
        } //Multimea B va avea n elemente
    qsort(B,n,sizeof(int),cmp);
    fclose(g);
    printf("Multimea B: ");
    for(i=0;i<n;i++)
        printf("%d ",B[i]);
    printf("\n");
    numar=atoi(argv[1]);
    poz=(int *)bsearch(&numar,B,n,sizeof(int),cmp);
    if (poz>0)
        printf("Numarul %d se gaseste in multimea B pe pozitia %d.\n",numar,poz-B+1);
    else
        printf("Numarul %d nu se gaseste in multimea B.\n",numar);
    FILE *h;
    h=fopen("multI.txt","wt"); // punctul f)
    I=(int *)malloc(500*sizeof(int));
    for(i=0;i<m;i++)
        {
            poz=(int *)bsearch(&A[i],B,n,sizeof(int),cmp);
            if (poz>0)
                {
                    I[k]=A[i];
                    k++;
                }
        } //Intersectia va avea k elemente
    fprintf(f,"Intersectia: ");
    for(i=0;i<k;i++)
        fprintf(h,"%d ",I[i]);
    FILE *fp=fopen("multR.txt","wt"); //punctul e)
    R=(int *)malloc((m+n-k)*sizeof(int)); //Formula cardinalului reuniunii
    for(i=0;i<m;i++)
        R[i]=A[i];
    int card=m;
    for(i=0;i<n;i++)
        {
            qsort(R,card,sizeof(int),cmp);
            poz=(int *)bsearch(&B[i],R,card,sizeof(int),cmp);
            if (!(poz>0))
                {
                    R[card]=B[i];
                    card++;
                }
        }
    qsort(R,card,sizeof(int),cmp);
    for(i=0;i<card;i++)
        fprintf(fp,"%d ",R[i]);
    free(A);
    free(B);
    free(I);
    free(R);
}