C language slide

1. Technical Chat
C Workshop
Day- 6

2. extern int g=5;
void abc()
{
int a;
static int s=5;
a=s--;
++g;
printf(“n %d %d %d”, a,s,g);
if(a>=3)
abc();
printf(“n %d %d %d”, a,s,g);
}
void xyz()
{
auto int a;
static int s;
a=++s;
--g;
printf(“n %d %d %d”, a,s,g);
if(a<=3)
xyz();
printf(“n %d %d %d”, a,s,g);
}
void main()
{
void xyz(void);
xyz();
abc();
}

3. O/p-
1 1 4
2 2 3
3 3 2
4 4 1
4 4 1
3 4 1
2 4 1
1 4 1
5 4 2
4 3 3
3 2 4
2 1 5
2 1 5
3 1 5
4 1 5
5 1 5

4. Classification of Recursion
● Internal Recursion Process
● External Recursion Process
● Whenever a recursion function is calling itself
then it is called internal recursion process.
● When one recursion function is calling another
recursion function then it is called external
recursion process.

5. extern int g=5;
void abc()
{
auto int a;
static int s=5;
a=s--;
++g;
printf(“n %d %d %d”, a,s,g);
if(a>=3)
abc();
printf(“%d %d %d”, a,s,g);
}
void main()
{
void xyz(void);
xyz();
}
void xyz()
{
int a;
static int s;
a=s++;
--g;
printf(“n %d %d %d”, a,s,g);
if(a<=1)
{
abc();
xyz();
}
printf(“n %d %d %d”, a,s,g);
}

6. O/p-
0 1 4
5 4 5
4 3 6
3 2 7
2 1 8
2 1 8
3 1 8
4 1 8
5 1 8
1 2 7
1 0 8
1 0 8
2 3 7
2 3 7
1 3 7
0 3 7

7. recursion by using main()
● By using auto variable it became stack overflow
● Because for every call auto variable will be
constructed.
void main()
{
int a= 5;
++a;
printf(“%d”, a);
if (a<=6)
main();
printf(“%d”,a);
}
O/p-
6666666666.........Stack overflow

8. void main()
{
static int s=2;
++s;
printf(“%d”,s);
if(s<=4)
main()
printf(“%d”,s);
}
O/p- 235555

9. Power of a number through recursion:
int power(int b, int e)
{
if (e<0)
return 0;
else if(e==0)
return 1;
else
return(b*power(b-e-1));
}
void main()
{
int a,b,p;
printf(“Enter value of a:”);
scanf(“%d”, &a);
printf(“Enter value of b:”);
scnaf(“%d”, &b);
p=power(a,b);
printf(“n %d^%d value is :
%d”, a,b,p);
}

10. Factorial through recursion.
void main()
{
int n,f;
int fact(int);
printf(“Enter a value:”);
scanf(“%d”, &n);
f=fact(n);
printf(“n %d fact value is: %d”,n,f);
}
int fact(int n)
{
if(n<0)
return 0;
else if(n<=1)
return 1;
else
return (n*fact(n-1));
}

11. Dangling Pointer
● A pointer variable which is pointing to a
dead or inactive location, is called
dangling pointer.

12. Function pointer
● A pointer variable which holds the address of the
function, is called function pointer.
● Function pointer calls are faster then normal
function calls.
● By using function pointer it is possible to pass a
function as a argument to another function.