1. Variable Storage Memory Locations (Logical) Variable Classes Stack
Heap
Program Code
Register
Variable Classes
Automatic (locals)
Parameters
Globals

2. Variable Types
Scalars
Arrays
Structs
Unions
Objects ?

3. Row Major Array Storage
char A[20][15][10];
1000
A[0][0][0]
. . .
1150
A[1][0][0]
1160
A[1][1][0]
1161
A[1][1][1]
3999
A[19][14][9]

4. Column Major Array Storage
char A[20][15][10];
1000
A[0][0][0]
1001
A[1][0][0]
. . .
1021
A[1][1][0]
1321
A[1][1][1]
3999
A[19][14][9]

5. OR (Row Major) char A[20][15][10]; 3999 A[0][0][0] . . . 3849
3839
A[1][1][0]
3838
A[1][1][1]
1000
A[19][14][9]

6. Array Declaration Algorithm
Dimension Node {
int min;
int max;
int size; }

7. Declaration Algorithm (2)
Doubly linked list of dimension nodes
Pass 1 – while parsing
Build linked list from left to right
Insert min, max
Size = size of an element
Append node to end of list
min = max = size = 1

8. Declaration Algorithm (3) Pass 2
Traverse list from tail to head
For each node, n, going “right” to “left”
Factor = n.max – n.min + 1
For each node, m, right to left starting with n
m.size = m.size * factor
For each node, n, going left to right
N->right->max = max; N->right->min = min
Delete first element of list

9. Array Declaration (Row Major)
int weight[ ][1..12][1..31];
list of “dimension” nodes
int min, max, size
size of element of this dimension
1448
124 4

10. Array Offset (Row Major)
Traverse list summing (max-min) * size
int weight[ ][1..12][1..31];
x = [2002][5][31]
( ) * (5-1) * (31-1) * 4
1448
124 4

11. Your Turn Assume “Show” A’s dimension list
int A[10][20][30];
Row major order
“Show” A’s dimension list
Show hypothetical 3-addr code for
X = A[2][3][4] ;
A[3][4][5] = 9

12. Your Turn 2 Assume “Show” A’s dimension list
int A[10][20][30];
Column major order
“Show” A’s dimension list
Show hypothetical 3-addr code for
X = A[2][3][4] ;
A[3][4][5] = 9