Hi guys,
I was running a simple code on Fedora 11. it has this error " segmentation fault". The code is too simple to have any mistakes........ Can anyone help me with this? What is this "segmentation fault".

Thank you very much.

#include "stdio.h"  
int main()
{
        int T[1001][4001]; 
        int i=0;
    int j=0;     
        for(j=0;j<1001;j++)
        { 
                    for(i=0;i<4001;i++)
                { 
                                T[j][i]=0; 
                        }
            }  

    printf("Thank you!\n");       

    return 0;
}

I saved this file as mainapp.cpp.

command line:

g++ mainapp.cpp -o test
./test

then it says segmentation fault........

Your array maybe too big. Try decreasing the size of the array and see if the seg fault goes away...G

Try defining you array like below:

#include "stdio.h"

int T[1001][4001];

int main()
{
int i=0;
int j=0;
for(j=0;j<1001;j++)
{
for(i=0;i<4001;i++)
{
T[j][i]=0;
}
}

printf("Thank you!\n");

return 0;
}

Also a seg fault is generally triggered when a user application tries to access an invalid address.

Your array maybe too big. Try decreasing the size of the array and see if the seg fault goes away...G

You are right, if I tried a smaller one like T[101][4001], it is ok.....

But the problem is, int T[1001][4001] is not big at all. And I need to define such arrays in my computation.

Do you know what the problem is?

You are right, if I tried a smaller one like T[101][4001], it is ok.....

But the problem is, int T[1001][4001] is not big at all. And I need to define such arrays in my computation.

Do you know what the problem is?

Yes look at my second solution

int T[1001][4001];
needs a huge memory that is equeal to

1001 * 4001 * 4 [sizeof(int) is 4 in linux]
that equeals to

4,000,000 * 4 byte approx
= 16,000,000 byte
= 16,000 KB (approx)
= 16 MB (approx)

due to this size only your system is giving a segmentation fault.

try your program with simply one line

int main()
{
int T[1001][4001];
return 0;
}

it should give a seg fault


if you are doing computation with numbers which takes atmost two byte u can use the "short" data type instead. It should then work fine.

thanks
hope thats of some help