problem initializing large double array

Question

Silly question from a new C programmer... I get a segmentation fault in the following code:

#include 
int main(void)
{
double YRaw[4000000]={0         


        

Answer 1

You tried to declare the entire array on the stack. Even if you have a terabyte of RAM, only a small, fixed portion of it is going to be dedicated to stack space. Large amounts of data need to be allocated on the heap, using malloc:

#include 
int main(void)
{
  double* YRaw = malloc(4000000 * sizeof(double));
  memset(YRaw, 0, 4000000 * sizeof(double));

  /* ... use it ... */

  free(YRaw); /* Give the memory back to the system when you're done */

  return 0;
}

See also: "What and where are the stack and heap?"