Data Structure about struct array - c

Question

Recently, I took a subject called Data structure. I've created a program to try out my knowledge but don't know why the program did not work. I can't figure it out so I post it here to ask for solution. I hope people can help me. I am newbie here. So please ignore my opinion if my opinion is found annoying.
#include <stdio.h>
int main()
{
struct Book
{
char title[50];
int year;
float price;
};
int i;
struct Book books[50];
books[0].title="Bullshit";
books[0].year=132;
books[0].price=146.9;
books[1]=(struct Book){"Money",1344,189.4
};
for(i=0;i<2;i++)
{
printf("Book Title is : %s\n",books[i].title);
printf("Book Year is %d\n",books[i].year);
printf("Book price is %3.2f\n",books[i].price);
printf("\n\n");
}
}

Answer 1

1 I would make declaration of struct rather outside main than inside
2 Try changing char title[50] to char *title
#include <stdio.h>
struct Book {
char *title;
int year;
float price;
};
int main() {
int i;
struct Book books[50];
books[0].title = "Bullshit";
books[0].year = 132;
books[0].price = 146.9;
books[1] = (struct Book) {"Money", 1344, 189.4
};
for (i = 0; i < 2; i++) {
printf("Book Title is : %s\n", books[i].title);
printf("Book Year is %d\n", books[i].year);
printf("Book price is %3.2f\n", books[i].price);
printf("\n\n");
}
}
Why it didn't worked before?
In c arrays are not assignable by = operator.
You could do something like instead title[0] = 'B'; title[1] = 'u', etc....(or use strcpy which does it for you).
char *x is not really an array, it's just pointer to single char.
If we write x = "abc", we are telling the compiler: set x to 'a', next byte to 'b', next to 'c', and next to 0(not '0', just zero).
And when you do printf("%s",x), the printf function prints chars from the place in memory specified by x until it see 0 byte.
char *x = "abcd";
char *y = x;
while(*y != 0){ // this loop acts like printf("%s",x);
printf("%c",*y);
y++;
}
See also this and this question.
Or if you are using c++, not c, use std::string:
#include <cstdio>
#include <string>
struct Book {
std::string title;
int year;
float price;
Book(std::string t, int y, float p) {
title = t;
year = y;
price = p;
}
};
int main() {
int i;
Book books[50];
books[0].title = "Bullshit";
books[0].year = 132;
books[0].price = 146.9;
books[1] = Book(std::string("Money"), 1344, 189.4);
for (i = 0; i < 2; i++) {
printf("Book Title is : %s\n", books[i].title.c_str());
printf("Book Year is %d\n", books[i].year);
printf("Book price is %3.2f\n", books[i].price);
printf("\n\n");
}
}

Answer 2

this
books[0].title="Bullshit";
is not valid. title is defined as char[50]. Either do
strcpy(books[0].title, "BS");
This will copy the bytes of BS to title. Or do
struct Book
{
char *title;
int year;
float price;
};
...
books[0].title = strdup("BS");
This sets title up as a pointer to a char string. strdup will allocate space for the string and copy BS to that space. You will have to free that allocated space.
Or - the best. Use std::string
struct Book
{
std::string title;
int year;
float price;
};
....
books[0].title = "BS";
And as a final thought - life goes better with std::vector instead of raw arrays