The document discusses various aspects of functions in C programming including passing values to functions, returning values from functions, and more advanced features like returning non-integer values, call by value/reference, and recursion. It provides examples of defining and calling functions, passing arguments, returning single and multiple values, and illustrates proper and improper usage of functions.

1. Break From The Outermost Loop
main( )
{
for ( i = 1 ; i <= 22 ; i+= 2 )
{
for ( j = 5 ; j <= 50 ; j++ )
{
for ( k = 1 ; k <= 9 ; k += 3 )
{
… …
if ( i + j % k >= 2 )
break ;
}
}
}
}
break ;
break ;
Go to work
only once
if ( i + j % k >= 2 )
if ( i + j % k >= 2 )
break ;
break ;

2. main( )
{
for ( i = 1 ; i <= 22 ; i+= 2 )
{
for ( j = 5 ; j <= 50 ; j++ )
{
for ( k = 1 ; k <= 9 ; k += 3 )
{
… …
if ( i + j % k >= 2 )
goto out ;
}
}
}
}
Better Way...
out :
;
Never use
a goto

3. main( )
{
in :
goto there ;
for ( i = 1 ; i <= 22 ; i+= 2 )
{
for ( j = 5 ; j <= 50 ; j++ )
{
there :
for ( k = 1 ; k <= 9 ; k += 3 )
{
… …
if ( i + j % k >= 2 )
} goto out ;
}
}
}
Where Am I...
out :
goto in ;

4. Control Instructions
Sequence
Decision
Repitition
Case
goto

5. Communication
main( )
{
int a = 10, b = 20, c = 30 ;
calsum ( ) ;
printf ( ”%d”, s ) ;
}
calsum( )
{
int a, b, c, s ;
}
int s ;
s = a + b + c ;
printf ( ”%d”, s ) ;
Garbage
Garbage

6. Passing Values
main( )
{
Actual
Arguments
int a = 10, b = 20, c = 30 ; int s ;
calsum ( a, b, c
) ;
printf ( ”%d”, s ) ;
}
calsum ( )
{
int s ;
}
int x, int y, int z
s = x + y + z ;
printf ( ”%d”, s ) ;
Garbage
Formal
Arguments
60

7. main( )
{
Returning Values
int a = 10, b = 20, c = 30, s ;
calsum ( a, b, c ) ;
}
calsum ( int x, int y, int z )
{
int ss ;
ss = x + y + z ;
return ( ss ) ;
}
s = calsum ( a, b, c ) ;
printf ( ”%d”, s ) ;
60
return ; Returns only
return ; Returns only
control
control
Return control
and value
Return control
and value
return ( ss ) ;
return ( 60 ) ;
return ( x + y + z ) ;

8. Are These Calls OK?
calsum ( a, 25, d ) ;
calsum ( 10 + 2, 25 % 3, d ) ;
calsum ( a, calsum ( 25, 10, 4 ), d ) ;
d = calsum ( a, 25, d ) * calsum ( a, 25, d ) + 23 ;
calsum ( int x, int y, int z )
{
int ss ;
ss = x + y + z ;
return ( ss ) ;
}
Nested calls are legal.
Call within an expression are legal.
Nested calls are legal.
Call within an expression are legal.

9. Returning More Than 1 Value
main( )
{
int a = 10, b = 20, c = 30 ;
ssu, mp p=r soudm ( par, obd, c ( )a ;, b , c ) ;
printf ( ”%d%d”, s, p ) ;
}
sumprod ( i n t x , i n t y , i n t z )
ss = x + y + z ;
pp = x * y * z ;
{
int ss, pp ;
return ( ss, pp ) ;
}
int s, p ;
A function can return only
1 value at a time

10. main( )
{
One More Try
int a = 10, b = 20, c = 30 ;
int s, p ;
s = sumprod ( a, b, c ) ;
p = sumprod ( a, b, c ) ;
printf ( ”%d%d”, s, p ) ;
} sumprod ( int x, int y, int z )
{
ss = x + y + z ;
pp = x * y * z ;
return ( ss ) ;
return ( pp ) ;
}
int ss, pp ;
60 60
Redundant

11. main( )
{
The Only Way Out
int a = 10, b = 20, c = 30 ; int s, p ;
s = sumprod ( a, b, c ) ;
p = sumprod ( a, b, c ) ;
printf ( ”%d%d”, s, p ) ;
}
, 1
, 2
sumprod ( int x, int y, int z, )
{
int ss, pp ;
ss = x + y + z ; pp = x * y * z ;
}
int code
if ( code == 1 )
return ( ss ) ;
else
return ( pp ) ;
Sum, Product,
Average, Variance
Standard Deviation

12. A Better Way
sumprod ( int x, int y, int z, int code )
{
int ss, pp ;
ss = x + y + z ;
pp = x * y * z ;
}
if ( code == 1 )
return ( ss ) ;
else
return ( pp ) ;
code == 1 ? return ( x + y + z ) : return ( x * y * z ) ;
return ( code == 1 ? x + y + z : x * y * z ) ;

13. ANSI V/s K R
calsum ( int x, int y, int z )
{
..
}
calsum ( int x, int y, int z )
{
..
}
calsum ( x, y, z )
int x, y, z ;
{
..
}
calsum ( x, y, z )
int x, y, z ;
{
..
}
ANSI
Kernighan
Ritchie

14. main( )
{
int y ;
printf ( ”Enter year” ) ;
scanf ( ”%d”, y ) ;
romanize ( y ) ;
}
romanize ( int yy )
{
int n, i ;
n = yy / 1000 ;
for ( i = 1 ; i = n ; i ++ )
printf ( ”m” ) ;
Decimal Roman
1000 m
500 d
100 c
50 l
10 x
5 v
1 i
}
Roman Equivalent
1998 m d c c c c l x x x x i i i
1998
v

15. A More General Call
main( )
{
int y ;
printf ( ”Enter year” ) ;
scanf ( ”%d”, y ) ;
, 1000 , ’m’
y romanize = romanise ( y ( y, 1000, ’) m’ ;
) ;
}
romanize ( int yy , int j , char ch
)
{
int n, i ;
n = yy / j ;
for ( i = 1 ; i = n ; i ++ )
printf ( ) ;
}
”%c”, ch
return ( yy % j ) ;

16. main( )
{
...
1998 md c c c c lx xx x v i ii
, ’m’
y = romanise ( y, 1000 ) ;
y = romanise ( y, 500, ’d’ ) ;
y = romanise ( y, 100, ’c’ ) ;
y = romanise ( y, 50, ’l’ ) ;
y = romanise ( y, 10, ’x’ ) ;
y = romanise ( y, 5, ’v’ ) ;
romanise ( y, 1, ’i’ ) ;
}
romanize ( int yy )
{
}
, int j, char ch
int n, i ;
n = yy / j ;
for ( i = 1 ; i = n ; i ++ )
printf ( ”%c”, ch ) ;
return ( yy % j ) ;
Works

17. Advanced Features of
Functions
Returning a non-integer value
Call by value / Call by reference
Recursion

18. Returning a Non-Integer Value
main( )
{
a = square ( 2.0 ) ;
b = square ( 2.5 ) ;
c = square ( 1.5 ) ;
printf ( ” %f %f %f ”, a, b, c, ) ;
square ( 2.0 ) ;
} square ( ) float x
{
float y ;
y = x * x ;
printf ( ” %f ”, y ) ;
return ( y ) ;
}
Function
Prototype
4.0 6.0 2.0
float a, b, c ; float square ( float ) ;
4.0
6.25
2.25
float square ( float x )

19. 115566 -- 116611 ((ee))