Segmentation Fault hmm?

Hey guys I'm trying to get this to work, it does the first loop in main and asks for the names/year etc, but once I type the year it says "Segmentation fault" and kills the program! If someone could please tell me what Segmentation Fault means that would be great, Also yes I realise I probably should be using fgets instead of fscan but i'm familiar with fscan so I'm sticking with it for this program. But if that's the actual issue then I guess I'll have to change it. Thanks!

[B]EDIT: Yay I fixed it, someone on IRC told me that I needed & infront of "scanf("%d", records[x].yearborn);" i.e "scanf("%d", &records[x].yearborn);", the only problem is I don't understand WHY :P If someone could help explain that'd be great!

Code:

#include <stdio.h>
 
struct rec
{
	char firstname[20];
	char lastname[20];
	int yearborn;
} records[5];
 
int main()
{
	int x;
	int y;
	for (x=0; x < 5; x++) 
	{
		printf("Please enter the FIRST name of #%d. member!\n", x+1);
		scanf("%s", records[x].firstname);
		printf("Please enter the LAST name of #%d. member!\n", x+1);
		scanf("%s", records[x].lastname);
		printf("Please enter the year this member was born!\n");
		scanf("%d", records[x].yearborn);
	}
	for (y=0; y < 5; y++)
	{
		printf("Record %d, First Name: %s\n", y, records[y].firstname);
		printf("Record %d, Last Name: %s\n", y, records[y].lastname);
		printf("Record %d, Year Born: %d\n", y, records[y].yearborn);
		printf("-------------------------------------\n");
	}
	return 0;
}

Change

Code:

scanf("%d", records[x].yearborn);

to

Code:

scanf("%d", &records[x].yearborn);

EDIT: I see someone already told you the answer 1 minute before i posted =D

Yup got that, but knowing WHY would be helpful

You were passing the value of yearborn to scanf. In order for a function to modify the value of one of the function parameters, that parameter needs to be the pointer to the variable, not the actual value. Putting "&" in front gets the pointer to the variable so scanf can change the pointers value.

Heres an example:

Code:

void ChangeMe(int a)
{
  a = 32;
}

int a = 16;
ChangeMe(a);
printf("%i\n", a); //It still prints 16 rather than 32.

You would use this instead:

Code:

void ChangeMe(int* a)
{
  *a = 32;
}

int a = 16;
ChangeMe(&a);
printf("%i\n", a); //a has been changed after calling ChangeMe

http://cpwiki.sourceforge.net/A_pointer_on_pointers
It is critical that you understand this.
Also read http://cpwiki.sourceforge.net/buffer_overrun and fix your scanf lines.
Even better is to use fgets.