Finding Adress of an Element in Array

When it comes to organizing and accessing elements in a multi-dimensional array, two prevalent methods are Row Major Order and Column Major Order.

1. Row Major Order

Row major ordering assigns successive elements, moving across the rows and then down the next row, to successive memory locations. In simple language, the elements of an array are stored in a Row-Wise fashion.
To find the address of the element using row-major order uses the following formula:

Address of A[I][J] = B + W * ((I – LR) * N + (J – LC))   

I = Row Subset of an element whose address to be found, 
J = Column Subset of an element whose address to be found, 
B = Base address, 
W = Storage size of one element store in an array(in byte), 
LR = Lower Limit of row/start row index of the matrix(If not given assume it as zero), 
LC = Lower Limit of column/start column index of the matrix(If not given assume it as zero), 
N = Number of column given in the matrix.

2. Column Major Order

If elements of an array are stored in a column-major fashion means moving across the column and then to the next column then it’s in column-major order. To find the address of the element using column-major order use the following formula:

Address of A[I][J] = B + W * ((J – LC) * M + (I – LR))  

I = Row Subset of an element whose address to be found, 
J = Column Subset of an element whose address to be found, 
B = Base address, 
W = Storage size of one element store in any array(in byte), 
LR = Lower Limit of row/start row index of matrix(If not given assume it as zero), 
LC = Lower Limit of column/start column index of matrix(If not given assume it as zero), 
M = Number of rows given in the matrix.

Arrays are fundamental data structures in computer science, and mastering them is crucial for success in the GATE exam. This article aims to provide concise yet comprehensive notes on arrays, covering essential concepts and strategies to help you tackle array-related questions in the GATE 2024 exam.