Question

I am just doing an experiment to put values in double dimensional array to a single dimensional array. Below is my code and result:

#include <iostream>
using namespace std;

int main()
{
int p[1][1];
int arrayA[4];

for(int i=0;i<2;i++){
    for(int j=0;j<2;j++)
    {
        p[i][j] = i+j;
    }
}
int *a = &(p[0][0]);
for(int k=0;k<4;k++)
{
    arrayA[k] = *a;
    cout << "*a:  " << *a << endl ;
    cout << "array[k] :" << arrayA[k] << endl;
    cout << "a:   " << a << endl;
    cout << "---------------------------" << endl;
    a++;
}
system("PAUSE");    
    }

and the result is:

But I have no idea why it missed the value of p1[0], which value should be 1. But instead, I got a weird number where it is from. Because this is weird to me that I can put the last number in the double dimensional array to the single dimensional array but not the number before.

So I hope somebody can tell me what happen to me code or my method of thinking. Thank you.

Answer 1

This results in an out of bounds on array p:

int p[1][1];
int arrayA[4];

for(int i=0;i<2;i++){
    for(int j=0;j<2;j++)
    {
        p[i][j] = i+j;
    }
}

Indexes on arrays run from 0 to N - 1, where N is the size of the array.