SIGSEGV(segmentation fault) error in dev c++

Question

when i have run this code in dev i have a segmentation fault. in line "*(ap + j) = new int[10];"

int main(){
    int** ap;
    for(int j=0;j<10;j++){
        *(ap + j) = new int[10];
        for(int k=0;k<10;k++){
            *(*(ap+j) +k) = 1;
        }
    }
return 0;
}

Answer 1

You never allocate any memory for ap. Something like:

int** ap;
ap = new int*[10];

is what you want.

Answer 2

You are allocating memory for the data but are not allocating memory for the pointer array. It might be enough for you to change the declaration of ap to int* ap[10];.

Answer 3

In *(ap + j) = new int[10]; you dereference memory location which is not allocated yet. First you have to allocate variable ap itself.

Answer 4

Your problem here is *(ap +j) = new ...

Where you are assigning memory for the location "ap+j", the problem is ap + j is not yet a valid memory location because you have not initialized ap. So when you add j to ap you go into uninitialized memory space and therefore get your segmentation fault.