将2-d数组传递给函数时出错

Question

The program is just for passing complete 2-d array to function.I am able to run the problem by hook or by crook but i didnt understood.I have written a program which i should have written threotically and which i have written to make it working(in comments) can anyone please explain me this issue??

#include<iostream>
#include<conio.h>
void print(bool *a);
using namespace std;
int main()
{
    bool arr[3][3]={1,1,1,1,0,0,0,1,1};
    print(arr[0]);//**This IS working but why  we need subscript 0 here only print(arr) should work?..**
    getch();
    return 0;
}
void print(bool *a)
{

    for(int i=0;i<3;i++)
    {
        for(int j=0;j<3;j++)
            {
                cout<<*(a+i*3+j)<<"|";//**cant we use cout<<a[i][j] here??In 1 d array it is working fine**
            }
            cout<<"--";
    }

}

Answer 1

void print(bool *a)

should be

void print(bool a[][3])

the compiler needs to know the size of second dimension in order to compute offset for addressing.

void print(bool a[][3], int rowSize)
{
   for(int i=0;i<rowSize;i++)
   {
     for(int j=0;j<3;j++)
     {
        cout<<a[i][j]<<"|";
     }
     cout<<"--";
}

In C++, you should prefer using vector<vector <bool> > over 2D dynamic array arr .

Answer 2

Use:

 void print(bool a[][3])

which is the correct prototype if you want to call print(arr);

Then you can use a[i][j] to access array elements in the print function body.

arr is an array of array 3 of bool and when passed to print function call the arr expression is converted to a pointer to an array 3 of bool .