how to find 2d array size in c++

Question

How do I find the size of a 2D array in C++? Is there any predefined function like sizeof to determine the size of the array?

Also, can anyone tell me how to detect an error in the getvalue method for arrays while trying to get a value which is not set?

Answer 1

Suppose you were only allowed to use array then you could find the size of 2-d array by the following way.

  int ary[][5] = { {1, 2, 3, 4, 5},                    {6, 7, 8, 9, 0}                  };    int rows =  sizeof ary / sizeof ary[0]; // 2 rows      int cols = sizeof ary[0] / sizeof(int); // 5 cols 

Answer 2

#include <bits/stdc++.h> using namespace std;   int main(int argc, char const *argv[]) {     int arr[6][5] = {         {1,2,3,4,5},         {1,2,3,4,5},         {1,2,3,4,5},         {1,2,3,4,5},         {1,2,3,4,5},         {1,2,3,4,5}     };     int rows = sizeof(arr)/sizeof(arr[0]);     int cols = sizeof(arr[0])/sizeof(arr[0][0]);     cout<<rows<<" "<<cols<<endl;     return 0; } 

Output: 6 5