Question

How to convert a 2D coordinate into 1D index in C++

Answer 1

#include <iostream>

int main(void)
{
    int array2d[4][5] = { { 1,   2,   3,   6,  0},
                          {-5,  -4,   0,   7,  9},
                          { 1,  18, 100,  14,  6},
                          { 9,  10,  27,  12, 13} };
  
    int rows = (sizeof(array2d) / sizeof(array2d[0]));
    int cols = (sizeof(array2d) / sizeof(array2d[0][0])) / rows;
  
    int i = 1, j = 3;
           
    int index = i * cols + j;
           
    std::cout << index;
}
  
 
  
/*
run:
  
8
 
*/

 

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