array declaration

Please allow me to make a beginner's question. I'd like to declare an array of structures for holding data of a worksheet:

Code:

struct row {
int name;
int age;
int dob;
...(many entries)...
};

main()
{
struct row worksheet[MAXROW];

....
}

and I got an error message "Segmentation fault (core dumped)" when MAXROW=500. (size of struct row = 5244byte)
As I did not get the error when MAXROW=10, the problem seems to be an available memory space, but I could also make it without the error under the following two versions of codes:

version1 (MAXROW=500)

Code:

struct row {
int name;
int age;
int dob;
...(many entries)...
} worksheet[MAXROW];

main()
{
....
}

version2 (MAXROW=500)

Code:

#include <stdlib.h>

struct row {
int name;
int age;
int dob;
...(many entries)...
};

main()
{
struct row *worksheet;
worksheet = calloc(MAXROW, sizeof(struct row));

....
}

Could anyone please point out what's wrong in the first code?

2622000 is the number of bytes your large array occupies.
Note that the typical stack allocation for local variables is 1MByte (you blow that away with one line of code!)

Thank you so much, that's explain everything. (I did not even know that there's upper limit for local variable size.)

Well you can usually change it, but exactly how you do that varies widely from one system to another.

For the problem you had, there are a number of easy ways out which don't involve stack usage. You could even have done this if you were worried about scope.

Code:

int main()
{
    static struct row worksheet[MAXROW]; ....

}

1Mb is usually plenty enough stack space for programs except ones which are massively recursive.

If you ever get to program embedded systems, you might find the stack space allocation harsh. Sometimes as low as a few Kb.

Thanks a lot again. Now I come to understand that there is usually no need of auto variable more than 1Mb, as in my case. static specifier works perfectly, I will go with it.

In the future, I would actually suggest you learn about dynamic memory and allocate enough to meet your demands instead of just brute forcing enough memory.
Dynamic memory may be a little complicated, but there have been many examples on the board in the past...

Hi, thank you for the advise. I studied a basic idea of dynamic memory allocation in K&R. Some fields of my database in fact contain strings whose length vary each row, so I should've used the method at least for that part.