C Mulitple definition/first defined here error

Question

I'm trying to write a bookstore program, and I'm getting an error saying "multiple definition" in my source code file at my function implementation.

Here is my Book.c file:

#include "Book.h"

void scanBook(book_t* bk) //error here
{
    //implementation here
}

Here is my Book.h file:

#pragma once
#include <stdio.h>

typedef char* str;    
typedef enum Genre {Education, Business, Novel} genre_t;

typedef struct Book{
    str ISBN;
    str title;
    str author;
    float price;
    int quantity;
    genre_t genre;
} book_t;

void scanBook(book_t* bk);

And here is my main.c file:

#include "Book.h"
#include "Book.c"

int main()
{
    return 0;
}

The error occurs at the scanBook function in Book.c but I don't know why, since I included the header file as well as #pragma once, and in the header file I declared the function. It says multiple definition of 'scanBook' and obj\Debug\Book.o .... first defined here.

Any help or clarification would be greatly appreciated!

Answer 1

Don’t do:

#include “Book.c"

in your main.c file.