CODEWITHSUNDEEP
c++stack-overflow
alexs2011
alexs2011

Reputation: 1

array of size 1 MB

#include<iostream>
#include <intrin.h>
using namespace std;
unsigned __int64 TimeValue=0;

unsigned __int64 rdtsc(void) 
{  
   return __rdtsc(); 
};

void time_start() { TimeValue=rdtsc(); }
long long time_stop() { 
    return (rdtsc()-TimeValue); 
}
int main()
{
    long x[262144],i,k,r;
    int j;
    x[0] = 0;
for (i=1; i<262144; i++)
{
    long r = rand()%i;
    x[i] = x[r];
    x[r] = i;
}
    time_start();
    for (j=0; j<1000; j++)
        for (k=0, i=0; i<262144; i++) 
            k = x[k];
    cout<<time_stop()/1000/262144;
}

In the program I need to create an array size of 1 megabyte. When debugging a program on the line long x [262144], an error occurs: An unhandled exception "0x00ff1997" in the "dgdxgdrfy.exe": 0xC00000FD: Stack overflow. Why is this and how to fix it?

Upvotes: 0

Views: 3024

Answers (5)

Felice Pollano
Felice Pollano

Reputation: 33252

You can use static long x[262144]; It does move the allocation outside the stack and you don't modify your code at all.

Upvotes: 1

Mark Ransom
Mark Ransom

Reputation: 308130

Local variables get allocated on the stack, but the stack is limited. You can probably increase the limit with a switch on the compiler.

The problem is the very large array you've declared. One simple fix will change it from being on the stack to being dynamically allocated:

std::vector<long> x(262144);

Upvotes: 3

PearsonArtPhoto
PearsonArtPhoto

Reputation: 39698

Basically, you should dynamically allocate the x array, as is seen in this article. The below example was pulled out from the text, if you change it to be appropriate for your case, it should work fine.

double *num; 
num = (double *) malloc (BUFSZ* sizeof(double))

Upvotes: 0

Ivaylo Strandjev
Ivaylo Strandjev

Reputation: 70929

This happens because a local array is allocated on the stack. You can avoid this by using a dynamic array(one created with new), a vector or by declaring the array in the global scope.

Upvotes: 2

Petar Minchev
Petar Minchev

Reputation: 47373

Try to declare it as a global variable - outside the main method(). Otherwise it will be allocated on the stack which is far smaller than the heap. Another solution is to use dynamic allocation with new, but this is more error prone.

Upvotes: 3

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