database.c

//A  program to manage database of books

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

struct
{
    char name[20];
    int ncopies;
    float cost;
} book;
void list(FILE *fp)
{
    rewind(fp);
    printf("\nNAME\tCOPIES\t\tCOST\n\n");
    while (fread(&book, sizeof(book), 1, fp) == 1)
    {
        printf("%s\t", book.name);
        printf("%d\t", book.ncopies);
        printf("%f\n", book.cost);
    }
    printf("\n");
}
int search(FILE *fp, char *name)
{
    unsigned flag = 0;
    rewind(fp);
    while (fread(&book, sizeof(book), 1, fp) == 1)
    {
        if (strcmp(name, book.name) == 0)
        {
            flag = 1;
            break;
        }
    }
    if (flag == 0)
        printf("\nName not found in file\n\n");
    return flag;
}
void display(FILE *fp)
{
    char name[50];
    printf("Enter the name of the book : ");
    scanf("%s", name);
    if (search(fp, name) == 1)
    {
        printf("\nName\t%s\n", book.name);
        printf("Copies\t%d\n", book.ncopies);
        printf("Cost\t%f\n\n", book.cost);
    }
}
void booksold(FILE *fp)
{
    char name[50];
    long size = sizeof(book);
    printf("Enter the name of the book to be sold : ");
    scanf("%s", name);
    if (search(fp, name) == 1)
    {
        if (book.ncopies > 0)
        {
            book.ncopies--;
            fseek(fp, -size, 1);
            fwrite(&book, sizeof(book), 1, fp);
            printf("One book sold\n");
            printf("Now number of copies = %d\n", book.ncopies);
        }
        else
            printf("Book is out of stock \n\n");
    }
}
void modify(FILE *fp)
{
    char name[50];
    long size = sizeof(book);
    printf("Enter the name of the book to be modified : ");
    scanf("%s", name);
    if (search(fp, name) == 1)
    {
        printf("Enter new data --->\n\n");
        printf("Enter book name : ");
        scanf("%s", book.name);
        printf("Enter no of copies : ");
        scanf("%d", &book.ncopies);
        printf("Enter cost of book : ");
        scanf("%f", &book.cost);
        fseek(fp, -size, 1);
        fwrite(&book, sizeof(book), 1, fp);
        printf("\nRecord is successfully modified....\n");
    }
}
void insert(FILE *fp)
{
    fseek(fp, 0, 2);
    printf("Enter book name : ");
    scanf("%s", book.name);
    printf("Enter the no of copies : ");
    scanf("%d", &book.ncopies);
    printf("Enter the cost of book  : ");
    scanf("%f", &book.cost);
    fwrite(&book, sizeof(book), 1, fp);
}
void del(FILE *fp)
{
    FILE *fptmp;
    char name[20];
    printf("Enter the name of book to be deleted from the database : ");
    scanf("%s", name);
    if (search(fp, name) == 0)
        return;
    fptmp = fopen("tempfile", "wb");
    rewind(fp);
    while (fread(&book, sizeof(book), 1, fp) == 1)
    {
        if (strcmp(name, book.name) != 0)
            fwrite(&book, sizeof(book), 1, fptmp);
    }
    fclose(fp);
    fclose(fptmp);
    remove("books");
    rename("tempfile", "books");
    printf("\nRecord deleted....\n");
    fp = fopen("books", "rb+");
}
int main(void)
{

    int choice;
    FILE *fp;
    fp = fopen("books", "rb+");
    if (fp == NULL)
    {
        fp = fopen("books", "wb+");
        if (fp == NULL)
        {
            puts("Error in openning file");
            exit(1);
        }
    }
    while (1)
    {
        printf("1. Insert a new record\n");
        printf("2. Delete a record\n");
        printf("3. Display record of a book\n");
        printf("4. Modify a record\n");
        printf("5. List all records\n");
        printf("6. Book sold\n");
        printf("7. Exit\n");
        printf("Enter Your choice :\n");
        scanf("%d", &choice);

        switch (choice)
        {
        case 1:
            insert(fp);
            break;
        case 2:
            del(fp);
            break;
        case 3:
            display(fp);
            break;
        case 4:
            modify(fp);
            break;
        case 5:
            list(fp);
            break;
        case 6:
            booksold(fp);
            break;
        case 7:
            fclose(fp);
            exit(1);
        default:
            printf("Wrong Choice\n");
        }
    }
    return 0;
}