1. Macro Expansion
# define LOWER 1
main( )
{
# define UPPER 10
Macro Expansion
Macro Template
int i ;
for ( i = LOWER ; i <= UPPER ; i++ )
printf ( ”n%d”, i ) ;
}
for ( i = for ( i = 11 ;; ii <<== 1100 ;; ii++++ ))

2. Macro Expansion
# define PI 3.14
main( )
{
33..114411552288
float r, a ;
printf ( ”Enter radius” ) ;
scanf ( ”%f”, &r ) ;
a = PI * r * r ;
printf ( ”n%f”, a ) ;
}
aa == 33..1144 ** rr ** rr ;;
# define PI 3.14
PI = 6.28 ;
# define PI 3.14
PI = 6.28 ;
float PI = 3.14 ;
PI = 6.28 ;
float PI = 3.14 ;
PI = 6.28 ;

3. Don’t Remember Constants
Plank’s Constant
6.634 * ….. 6.023 * …..
Avogadro’s Number
# define PLANK 6.634E-24
main( )
{
a = PLANK * … ;
b = PLANK / …. ;
c = PLANK + … ;
d = PLAN - …. ;
}
Error
Detected

4. Types Of Macros
Macros With
Arguments
Simple Macros

5. Macros With Arguments
# define PI 3.14
# define AREA ( x ) PI * x * x
main( )
{
float r, a ;
scanf ( ”%f”, r ) ;
a = AREA ( r ) ;
printf ( ”n%f”, a ) ;
a = area ( r ) ;
}f
Order is
unimportant
float area ( float rr ) ;
loat area ( float rr )
{
Order is
unimportant
Macros - Faster
Functions - Less Space
return ( PI * rr * rr ) ;
}
aa == 33..1144 ** rr ** rr ;;
Macros - Faster
Functions - Less Space

6. Macros With Arguments
# define S ( x ) x * x
main( )
{
Alt F Dos Shell
C CPP PR1.C
C exit
Alt F Dos Shell
C CPP PR1.C
C exit
int i, j, k, l, x, n = 2 ;
i = S ( 4 ) ;
j = S ( 2 + 2 ) ;
k = S ( 3 + 1 ) ;
l = S ( 1 + 3 ) ;
m = S ( ++n ) ;
printf ( ”%d %d %d %d %d %d”, i, j, k, l, n, x ) ;
}
jj == 22 ++ 22 ** 22 ++ 22 ;;
kk == 33 ++ 11 ** 33 ++ 11 ;;
ii == 11 ++ 33 ** 11 ++ 33 ;;
ii == 44 ** 44 ;;
mm == ++++nn ** ++++nn ;;
1166 88 77 77 44 1166

7. Conditional Compilation
main( )
{
scanf ( .. ) ; /* input */
..
.. /* formula */
..
}
..
..
..
/*
*/

8. Conditional Compilation
main( )
{
2 Solutions :
- # define YES
- Delete # ifdef, # endif
scanf ( .. ) ; /* input */
..
.. /* formula */
..
}
..
..
..
# ifdef YES
# endif
2 Solutions :
- # define YES
- Delete # ifdef, # endif

9. Miscellaneous Directives
# define YES 10 main( )
{
a = YES - .. ;
printf ( ”YES” ) ;
}f
( )
{
int YES ;
}
a = YES + .. ;
# define YES 20
# undef YES
Redefinition
OK
Never
Replaced

10. # pragma
# pragma inline
main( )
{
asm stc
asm pushf
asm pop flags
..
}
..
..
..
..
F7, F8, F9, Ctrl F9
Won’t Work

11. How much C
Data Types
int
char
float
long
double
short
signed
unsigned
near
far
10 %?
Control Instruc.
if
else
for
while
do
break
continue
switch
case
default
Storage Classes
auto
register
static
extern
Control Instruc.
if
30 %? else
for
20 % ?
while
do
break
continue
switch
case
default
Storage Classes
auto
register
static
extern
goto
return
void
Data Types
int
char
float
long
double
short
signed
unsigned
near
far
2277 // 3322

12. Arrays
main( )
{
int i ;
printf ( ”Enter Marks” ) ;
scanf ( ”%d %d %d”, m1, m2, m3 ) ;
per = ( m1 + m2 + m3 ) / 3 ;
printf ( ”%d”, per ) ;
}
int m1, m2, m3, per ;
for ( i = 1 ; i = 10 ; i++ )
{
}
printf ( ”%d”, per ) ;

13. Choices Available
Use 10 variables each holding 1 value
Use 1 variable holding all 10 values
Array
What is an Array?
Array is a variable capable of
holding more than 1 value at a time

14. Nothing Different
per = { 32, 62, 65, 42, 48, 70, 80, 86, 92, 68 }
per3 per1 per6 per10
In General peri
subscript
H2O
superscript
Screen
per peri
i
ppeerr (( ii )) ppeerr [[ ii ]]
H2O

15. main( )
{
int i ;
Array?
0 9
0
0
printf ( ”Enter Marks” ) ;
scanf ( ”%d %d %d”, m1, m2, m3 ) ;
per[ i ] = ( m1 + m2 + m3 ) / 3 ;
}
int m1, m2, m3, per[ 10 ] ;
for ( i = 1 ; i = 10 ; i++ )
{
}
0 9
for ( i = 1 ; i = 10 ; i++ )
printf ( ”%d”, per[ i ] ) ;
A
Screen

16. Initializing Arrays
main( ) int i = 2 ;
{
optional
int a[ ] = { 7, 6, 11, -2, 26 } ;
int b[ 10 ] ; compulsory
int c[ 1 0 ] = { 16, 13, -8, -7, 25 } ;
printf ( ”%d%d”, sizeof ( a ), sizeof ( b ) ) ;
printf ( ”%d%d”, a[ 0 ], b[ 0 ] ) ;
scanf ( ”%d%d%d”, c [ 7 ] , c [ 8 ] , c [ 9 ] ) ;
c[ 5 ] = 3 + 7 % 2 ;
c[ 6 ] = c[ 1 ] + c[ 3 ] / 16 ;
}
10 20
int i ;
i = 2 ;
7 G

17. Moral
Arrays can be initialized
Array elements can be scanned
Array elements can be calculated
Arithmetic on array elements is allowed
Then how are they different?

18. Storage
j
400
main( )
{
int i = 3, j = 20, k = -5, l = 7, m = 11 ;
int a[ ] = { 3, 20, -5, 7, 11 } ; int ii ;
printf ( ”%u %u %u %u %u”, i, j, k, l, m ) ;
for ( ii = 0 ; ii = 4 ; ii++ )
printf ( ”%u”, a[ ii ] ) ;
502 504 506 508 510
a[0] a[1] a[2] a[3] a[4]
3 20 -5 7 11
502 504 506 508 510
100
}
m
600
400 500 700 600
3 i
100
20
k
-5
500
7 l
700
11
a[ ] = { 2, 1.4, ’A’, 6 } ;
int
- Adjacency
- Similarity

19. Bounds Checking
main( )
{
a[0] a[1] a[2] a[3] a[4] a[5] a[6]
3 60 -5 7 11
500 502 504 506 508
int a[ ] = { 3, 60, -5, 7, 11 } ;
int i ;
for ( i = 0 ; i = 4 ; i++ )
0
0
printf ( ”%d”, a [ i ] ) ;
}
a[ i ] = a[ i ] * 2 ;
for ( i = 0 ; i = 4 ; i++ )
510 512
Subscript out
of range

20. So ...
Arrays are variables capable of storing
multiple values
Array elements are stored in adjacent
memory locations
Checking the bounds of an array is
programmer’s responsibility

21. main( ) Selection Sort
{
int a[ ] = { 17, 6, 13,12, 2 } ;
int i, j, t ;
for ( i = 0 ; i = 3 ; i++ )
{
for ( j = i +
1 ; j = 4 ; j++ )
{
if ( a[ i ] a[ j ] )
{
t = a [ i ] ; a[ i ] = a[ j ] ;
a[ j ] = t ;
}
}
}
for ( i = 0 ; i = 4 ; i++ )
printf ( ”%d”, a[ i ] ) ;
}
j
17 6 13 12 2 i
6 17 13 12 2 0 - 1
6 17 13 12 2
0 - 2
6 17 13 12 2
0 - 3
2 17 13 12 6
0 - 4
2 13 17 12 6
1 - 2
2
12 17 13 6 1 - 3
2
6 17 13 12 1 - 4
2 6
13 17 12
2 6
12 17 13
2 6 12
2 - 3
2 - 4
13 17 3 - 4

22. Bubble Sort main( )
{
int a[ ] = { 17, 6, 13, 12, 2 } ;
int i, j, t ;
for ( j = 0 ; j = 3 ; j++ )
{
- j
for ( i = 0 ; i = 3 ; i++ )
{
if ( a[ i ] a[ i + 1 ] )
{
t =a[ i ] ; a[ i ] = a[ i + 1 ] ;
a[ i + 1 ] = t ;
}
}
}
for ( i = 0 ; i = 4 ; i++ )
printf ( ”%d”, a[ i ] ) ;
}
17 6 13 12 2 i
6 17 13 12 2 0 - 1
i+1
6 13 17 12 2
1 - 2
6 13 12 17 2
2 - 3
6 13 12 2 17
3 - 4
6 13 12 2 0 - 1
6 12 13 2
6 12 2 13
6 12 2
6 2 12
2 6
1 - 2
2 - 3
17
17
17
13 17 0 - 1
1 - 2
13 17
12 13 17 0 - 1

23. Sorting Procedures
Selection Sort
Bubble Sort
Shell Sort
Shuttle Sort
Heap Sort
Merge Sort
Radix Sort
Quick Sort
qsort( )
Recursion
Fastest?
n2
log2n

24. main( )
{
Quick Sort At Work
int a[ ] = {17, 6, 13, 12, 2 } ;
qsort ( a, 5, sizeof ( int ), fun ) ;
for ( i = 0 ; i = 4 ; i++ )
printf ( ”n%d”, a[i] ) ;
}
fun ( int *i, int *j )
{
return ( *i - *j ) ;
}
int i ;
int fun ( int *, int * ) ;
Comparison
Function

25. Chapter 7
Pg 209-212
244-249 (C)
Chapter 7
Pg 209-212
244-249 (C)
CChhaapptteerr 77