Question

An array T[50][20] is stored in the memory along the column with each element occupying 4 bytes. Find out the base address and address of the element T [30][15], if the element T[25][10] is stored at the memory location 9800.

Answer 1

T[50][20]

No. of Rows(i.e., R) = 50

No. of Cols(i.e., C) = 20

Element size(W) = 4 bytes

T[I][J] = T[30][15] => I=30, J=15

Address of T[25][10] = 9800

Base Address (B) =?

Lowest Row (i.e., lr) = 0

Lowest Col (i.e., lc) = 0

Formula to calculate address in Column Major arrangement is:

T[P][Q] = B + W[(P - lr) + R(Q - lc )]

T[25][10] = B + 4((25 – 0) + 50(10 – 0))

9800 = B + 4(525) (∵ T[25][10] = 9800 given)

9800 = B + 2100

=> B = 9800 – 2100

= 7700 Parallely, T[I][J] = B + W[(I - lr ) + R(J - lc )]

T[30][15] = 7700 + 4[(30 – 0) + 50(15 – 0)]

= 7700 + (4 x 780)

= 7700 + 3120

= 10820