인프런 커뮤니티 질문&답변

#define CRTSECURE_NO_WARNINGS

#include <stdio.h>

#include <stdlib.h>

#include <conio.h>

#define SLEN 101

struct book

{

char name[SLEN];

char author[SLEN];

};

void print_books(const struct book* books, int n);

void write_books(const char* filename, const struct book* books, int n);

struct book* read_books(const char* filename, int* n);

int main()

{

int temp;

int n = 3;

struct book* my_books = (struct book*)malloc(sizeof(struct book) * n);

if (!my_books) {

printf("Malloc failed");

exit(1);

}

my_books[0] = (struct book){ "The Great Gatsby", "F. Scott Fitzgerald" };

my_books[1] = (struct book){ "Hamlet", "William Shakespeare" };

my_books[2] = (struct book){ "The Odyssey", "Homer" };

print_books(my_books, n);

printf("\nWriting to a file.\n");

write_books("books.txt", my_books, n);

free(my_books);

n = 0;

printf("Done.\n");

printf("\nPress any key to read data from a file.\n\n");

temp = _getch();

my_books = read_books("books.txt", &n);

print_books(my_books, n);

free(my_books);

n = 0;

return 0;

}

void print_books(const struct book* books, int n)

{

for (int i = 0; i < n; ++i)

{

printf("Book %d : \"%s\" written by \"%s\"\n", i + 1, books[i].name, books[i].author);

}

}

void write_books(const char* filename, const struct book* books, int n)

{

FILE* fw;

if ((fw = fopen(filename, "w")) == NULL)

{

fprintf(stderr, "Can't open \"%s\" file.\n", filename);

exit(EXIT_FAILURE);

}

fwrite(books, sizeof(struct book), n, fw);

fclose(fw);

}

struct book* read_books(const char* filename, int* n)

{

FILE* fp;

if ((fp = fopen(filename, "r")) == NULL)

{

fprintf(stderr, "Can't open \"%s\" file.\n", filename);

exit(EXIT_FAILURE);

}

fseek(fp, 0, SEEK_END);

long file_size = ftell(fp);

rewind(fp);

struct book* all_books;

int si = file_size / sizeof(struct book);

*n = si;

all_books = (struct book*)malloc(sizeof(struct book) (n));

if (all_books == NULL)

{

printf("Failed");

return NULL;

}

fread(all_books, sizeof(struct book), *n, fp);

fclose(fp);

return all_books;

}

예제를 풀다보니 바이너리형식으로 추가,저장되는 코드로 만들어 버렸는데 이 경우에는 메모장에서 텍스트를 추가할 수 없으니 틀렸다고 보는게 맞겠죠?