Segmentation fault on large array sizes

Question

The following code gives me a segmentation fault when run on a 2Gb machine  but works on a 4GB machine   int main        int c 1000000      cout  lt  lt   done n      return 0      The size of the array is just 4Mb  Is there a limit on the size of an array that can be used in c

User · Answer

You array is being allocated on the stack in this case attempt to allocate an array of the same size using alloc

User · Answer

You re probably just getting a stack overflow here   The array is too big to fit in your program s stack address space   If you allocate the array on the heap you should be fine  assuming your machine has enough memory   int  array   new int 1000000    But remember that this will require you to delete   the array   A better solution would be to use std  vector lt int gt  and resize it to 1000000 elements

User · Answer

Because you store the array in the stack  You should store it in the heap  See this link to understand the concept of the heap and the stack

User · Answer

In C or C   local objects are usually allocated on the stack  You are allocating a large array on the stack  more than the stack can handle  so you are getting a stackoverflow   Don t allocate it local on stack  use some other place instead  This can be achieved by either making the object global or allocating it on the global heap  Global variables are fine  if you don t use the from any other compilation unit  To make sure this doesn t happen by accident  add a static storage specifier  otherwise just use the heap   This will allocate in the BSS segment  which is a part of the heap   static int c 1000000   int main        cout  lt  lt   done n      return 0      This will allocate in the DATA segment  which is a part of the heap too   int c 1000000        int main        cout  lt  lt   done n      return 0      This will allocate at some unspecified location in the heap   int main        int  c   new int 1000000      cout  lt  lt   done n      return 0

User · Answer

Also  if you are running in most UNIX  amp  Linux systems you can temporarily increase the stack size by the following command   ulimit -s unlimited   But be careful  memory is a limited resource and with great power come great responsibilities

[c++] Segmentation fault on large array sizes

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