blood camp

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

struct patient{
    char name[50];
    int age;
    char phone[50];
    char bgroup[30];
    char hospital[500];
};
struct donor{
    char name[50];
    int age;
    char phone[50];
    char bgroup[30];
    char address[500];
};

int main()
{
    int a,i=0,j=0,dummy;
    struct patient parray[100];
    struct donor darray[100];
    printf("Welcome to XYZ Blood Donation\n\n\n");
    for(;;){
        printf("1. Registration \n2. Donor list \n3. Patient list \n4. Exit \n");
        scanf("%d",&a);

        if(a==1)
        {
            printf("[Note: Don't use any space between your information]\n\n");
            int b;
            printf("1. Registration as Patient \n2. Registration as Donor \n");
            scanf("%d",&b);
            if(b==1){
                printf("Name: ");
                scanf("%s",&parray[i].name);
                printf("Age: ");
                scanf("%d",&parray[i].age);
                printf("Phone: ");
                scanf("%s",&parray[i].phone);
                printf("Blood Group: ");
                scanf("%s",&parray[i].bgroup);
                printf("Hospital: ");
                scanf("%s",&parray[i].hospital);
                scanf("%c",&dummy);
                printf("\n");
                i++;
            }
            else if(b==2)
            {
                printf("Name: ");
                scanf("%s",&darray[j].name);
                printf("Age: ");
                scanf("%d",&darray[j].age);
                printf("Phone: ");
                scanf("%s",&darray[j].phone);
                printf("Blood Group: ");
                scanf("%s",&darray[j].bgroup);
                printf("Address: ");
                scanf("%s",&darray[j].address);
                scanf("%c",&dummy);
                printf("\n");
                j++;
            }
        }
        else if(a==2)
        {
            for(int k=0;k<j;k++){
                printf("\n");
                printf("%d \n",k+1);
                printf("Name: ");
                printf("%s \n",darray[k].name);
                printf("Age: ");
                printf("%d \n",darray[k].age);
                printf("Phone: ");
                printf("%s \n",darray[k].phone);
                printf("Blood Group: ");
                printf("%s \n",darray[k].bgroup);
                printf("Address: ");
                printf("%s \n",darray[k].address);
                printf("\n\n");
            }
        }
        else if(a==3)
        {
            for(int k=0;k<i;k++){
                printf("\n");
                printf("%d \n",k+1);
                printf("Name: ");
                printf("%s \n",parray[k].name);
                printf("Age: ");
                printf("%d \n",parray[k].age);
                printf("Phone: ");
                printf("%s \n",parray[k].phone);
                printf("Blood Group: ");
                printf("%s \n",parray[k].bgroup);
                printf("Hospital: ");
                printf("%s \n",parray[k].hospital);
                printf("\n\n");
            }
        }
        else{
            break;
        }
    }

    return 0;
}