CODEWITHSUNDEEP
c++
Daniel Gratz
Daniel Gratz

Reputation: 817

Run time error with array

I can't understand why I get the run time error:

the variable ia is being used without being initialized.

However, as far as I can see, I have initialized it.

#include <iostream>
using namespace std;

int main()
{
    //array dimensions
    const int row_size = 2;
    const int col_size = 4;

    //array definition
    int ia[row_size][col_size] = {{0, 1, 2, 3},{5, 6, 7, 8}};

    cout << ia[2][4];

    system("PAUSE");
    return 0;
}

Upvotes: 0

Views: 132

Answers (4)

Mateen Ulhaq
Mateen Ulhaq

Reputation: 27271

ia[2][4]

doesn't exist.

ia[0..1][0...3]

all exist, however.

Try:

cout << ia[1][3];

Arrays in C++ start with the index 0. 1 is actually the 2nd element. So:

int a[2] = {42, 50};

std::cout << a[0] << a[1];   // prints 4250
std::cout << a[2];           // a[2] doesn't exist!

Upvotes: 1

DeCaf
DeCaf

Reputation: 6116

Arrays are 0-based, i.e. the first element in an array a is a[0]. So the last element in an array of 4 elements would be a[3]. In your case ia[1][3] would give you the sought element I believe.

Upvotes: 0

Draco Ater
Draco Ater

Reputation: 21226

Array indexes start from 0, so your ia[2][4] will be out of bounds. Should be ia[1][3].

Upvotes: 0

Danra
Danra

Reputation: 9926

C++ array indexes are zero-based. So to access the fourth column of the second row, you need to access ia[1][3].

Upvotes: 5

Related Questions