Use 2D-arrray. Segmentation fault - C++

Question

I'm doing some exercise online, so I have some problems. I don't know where is problem in my code. It's return Segmentation fault when I run code! My code below:

#include <iostream>

using namespace std;


int main() {
    int n, q, buff;
    int k[100000], i[100000], j[100000], a[100000][300000];
    int c;



   cin >> n >> q;


    for(buff=0; buff<n; buff++) {
        cin >> k[buff];
        //array
        for(c = 0;c < k[buff]; c++) {
           cin >> a[buff][c];  // <-- I think problem is here!
       }
    }


    for(buff = 0; buff < q; buff++) {
        cin >> i[buff];
    }


    for(buff = 0; buff < q; buff++) {
        cin >> j[buff];
    }   


    return 0;
}

Please help me! Sorry for my english.

These arrays are way too big to be allocated locally (on stack). — Eugene Sh., May 10 '17 at 18:09

score 1 · Accepted Answer · edited May 23 '17 at 12:02

1

Use of such large arrays in the stack causes stack overflow. See Getting a stack overflow exception when declaring a large array.

Use std::vector instead.

std::vector<int> k{100000};
std::vector<int> i{100000};
std::vector<int> j{100000};
std::vector<std::vector<int>> a{100000, std::vector<int>{300000}};

edited May 23 '17 at 12:02

Community

1
1

answered May 10 '17 at 18:21

R Sahu

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Hey. That's the name of the website. – Katana314 May 10 '17 at 19:49
This is my snippet: https://pastebin.com/E0biLAKL, however, It's not work! – Haniz May 23 '17 at 06:54
You are using `int n,p,i,j,c,a[100000][100000];` `a` is still large array, – R Sahu May 23 '17 at 15:22

score 0 · Answer 2 · answered May 10 '17 at 18:29

You are trying to create an array of 30000000000 integers.
Considering 64-bit system, size of int = 4 bytes, therefore total required size is around 120 GB, which is not available on the system stack.

This is the reason for stack overflow error.

Solution, use vectors instead of arrays in this situation.

Use 2D-arrray. Segmentation fault - C++

2 Answers2