1. C Programming - Functions
Organized By: Vinay Arora
Assistant Professor, CSED
Thapar University, Patiala

2. Main program & its sub parts
Function is also known as sub-program or module.
Function is a self contained block of statements that perform coherent task of
some kind.
Vinay Arora
CSED

3. Program-1
#include<stdio.h>
#include<conio.h>
void main()
{
clrscr();
printf("n Message for You");
printf("n Department of Civil Engineering");
getch();
}
Vinay Arora
CSED

4. Program-1 (output)
Vinay Arora
CSED

5. Program-2
#include<stdio.h>
#include<conio.h>
void main()
{
clrscr();
message();
printf("n Department of Civil Engineering");
getch();
}
message()
{
printf("n Message for You");
}
Vinay Arora
CSED

6. Program-2 (output)
Vinay Arora
CSED

7. Program-3
#include<stdio.h>
#include<conio.h>
void message();
void main()
{
clrscr();
message();
printf("n Department of Civil Engineering");
getch();
}
void message()
{
printf("n Message for You");
}
Vinay Arora
CSED

8. Program-3 (output)
Vinay Arora
CSED

9. Program-4
#include<stdio.h> void civil()
#include<conio.h> {
printf("nCivil Engg.");
void civil(); }
void computer();
void electronics(); void computer()
{
void main() printf("nComputer Engg.");
{ }
clrscr();
void electronics()
civil(); {
computer(); printf("nElectronics Engg.");
electronics(); }
printf("nnDepartments at Thapar");
getch();
}
Vinay Arora
CSED

10. Program-4
#include<stdio.h> void civil()
#include<conio.h> {
printf("nCivil Engg.");
void civil(); }
void computer();
void electronics(); void computer()
{
void main() printf("nComputer Engg.");
{ }
clrscr();
void electronics()
civil(); {
computer(); printf("nElectronics Engg.");
electronics(); }
printf("nnDepartments at Thapar");
getch();
}
Vinay Arora
CSED

11. Program-4 (output)
Vinay Arora
CSED

12. Program-5
#include<stdio.h> void civil()
#include<conio.h> {
printf("nCivil Engg.");
void civil(); computer();
void computer(); }
void electronics();
void computer()
void main() {
{ printf("nComputer Engg.");
clrscr(); electronics();
}
civil();
void electronics()
printf("nnDepartments at Thapar"); {
printf("nElectronics Engg.");
getch(); }
}
Vinay Arora
CSED

13. Program-5
#include<stdio.h> void civil()
#include<conio.h> {
printf("nCivil Engg.");
void civil(); computer();
void computer(); }
void electronics();
void computer()
void main() {
{ printf("nComputer Engg.");
clrscr(); electronics();
}
civil();
void electronics()
printf("nnDepartments at Thapar"); {
printf("nElectronics Engg.");
getch(); }
}
Vinay Arora
CSED

14. Program-5 (output)
Vinay Arora
CSED

15. Program-6
#include<stdio.h> void civil()
#include<conio.h> {
printf("nCivil Engg.");
void civil(); }
void main()
{
clrscr();
civil();
civil();
printf("nnDepartments at Thapar");
getch();
}
Vinay Arora
CSED

16. Program-6
#include<stdio.h> void civil()
#include<conio.h> {
printf("nCivil Engg.");
void civil(); }
void main()
{
clrscr();
civil();
civil();
printf("nnDepartments at Thapar");
getch();
}
Vinay Arora
CSED

17. Program-6 (output)
Vinay Arora
CSED

18. Program-7
#include<stdio.h>
#include<conio.h>
void main()
{
int a,b,c;
clrscr();
printf("Enter Numbers for Additionn");
printf("Enter 1st Number:t");
scanf("%d",&a);
printf("Enter 2nd Number:t");
scanf("%d",&b);
c=a+b;
printf("Result after Addition is:%d",c);
getch();
}
Vinay Arora
CSED

19. Program-7 (output)
Vinay Arora
CSED

20. Program-8
#include<stdio.h> void sum()
#include<conio.h> {
int a,b,c;
void sum(); printf("Enter Numbers for Additionn");
void main() printf("Enter 1st Number:t");
{ scanf("%d",&a);
clrscr(); printf("Enter 2nd Number:t");
sum(); scanf("%d",&b);
getch();
} c=a+b;
printf("Result after Addition is:%d",c);
}
Vinay Arora
CSED

21. Program-8 (output)
Vinay Arora
CSED

22. Program-9
#include<stdio.h> void sum(int x,int y)
#include<conio.h> {
int z;
void sum(); z=x+y;
void main() printf("Result after Addition is:%d",z);
{ }
int a,b,c;
clrscr();
printf("Enter Numbers for Additionn");
printf("Enter 1st Number:t");
scanf("%d",&a);
printf("Enter 2nd Number:t");
scanf("%d",&b);
sum(a,b);
getch();
}
Vinay Arora
CSED

23. Program-9 (output)
Vinay Arora
CSED

24. Program-10
#include<stdio.h> int sum(int x,int y)
#include<conio.h> {
int z;
int sum(); z=x+y;
void main() return (z);
{ }
int a,b,c;
clrscr();
printf("Enter Numbers for Additionn");
printf("Enter 1st Number:t");
scanf("%d",&a);
printf("Enter 2nd Number:t");
scanf("%d",&b);
c=sum(a,b);
printf("Result after Addition is:%d",c);
getch();
}
Vinay Arora
CSED

25. Program-10 (output)
Vinay Arora
CSED

26. Program-11
#include<stdio.h> int increment(int x)
#include<conio.h> {
x++;
int increment(); return (x);
void main() }
{
int a,b,c;
clrscr();
printf("Enter Numbert");
scanf("%d",&a);
c=increment(a);
printf("Result after Increment will be:%d",c);
getch();
}
Vinay Arora
CSED

27. Program-11 (output)
Vinay Arora
CSED

28. Program-12
#include<stdio.h>
#include<conio.h>
void display();
void main()
{
int a=20;
clrscr();
display(a);
getch();
}
void display(int x)
{
int y=27;
printf("Value passed from main function is %dn",x);
printf("Value present in display function is %d",y);
}
Vinay Arora
CSED

29. Program-12 (output)
Vinay Arora
CSED

30. Program-13
#include<stdio.h> void display()
#include<conio.h> {
int x=25;
void display();
void main() printf("Value of x in display function is %d",x);
{ }
int x=20;
clrscr();
printf("Value of x in main function %dn",x);
display();
getch();
}
Vinay Arora
CSED

31. Program-13 (output)
Vinay Arora
CSED

32. Program-14
#include<stdio.h> void display(int x)
#include<conio.h> {
x=77;
void display();
void main() printf("Value of x in display function is %d",x);
{ }
int x=20;
clrscr();
printf("Value of x in main function %dn",x);
display();
getch();
}
Vinay Arora
CSED

33. Program-14 (output)
Vinay Arora
CSED

34. Program-15
#include<stdio.h> int increment(int a)
#include<conio.h> {
a++;
void display(); return (a);
void main() }
{
int a,b; int decrement(int a)
clrscr(); {
a--;
printf("Enter Numbert"); return (a);
scanf("%d",&a); }
b=increment(a);
printf("nValue after increment is %dt",b);
b=decrement(a);
printf("nValue after decrement is %dt",b);
getch();
}
Vinay Arora
CSED

35. Program-15 (output)
Vinay Arora
CSED

36. Program-17
#include<stdio.h>
#include<conio.h>
int increment();
void main()
{
int i=10,j=20,k=30;
clrscr();
printf("%dt%dt%dn",i,j,k);
printf("%dt%dt%dn",i,j);
printf("%dn",i,j);
getch();
}
Vinay Arora
CSED

37. Program-17 (output)
Vinay Arora
CSED

38. Program-18
#include<stdio.h>
float square(float x)
#include<conio.h>
{
float y;
float square(float);
y=x*x;
void main()
return(y);
{
}
float a,b;
clrscr();
printf("Enter any Number:");
scanf("%f",&a);
b=square(a);
printf("Square of number entered is %ft",b);
getch();
}
Vinay Arora
CSED

39. Program-18 (output)
Vinay Arora
CSED

40. Program-19
#include<stdio.h> int factorial(int x)
#include<conio.h> {
int f=1,i;
void main()
{ for(i=x;i>=1;i--)
int a,fact; f=f*i;
clrscr();
return(f);
printf("Enter any Number:"); }
scanf("%d",&a);
fact=factorial(a);
printf("Factorial Value is = %dn",fact);
getch();
}
Vinay Arora
CSED

41. Program-19 (output)
Vinay Arora
CSED

42. Program-20 (Recursion in C)
#include<stdio.h> int rec(int x)
#include<conio.h> {
int f;
int rec(int);
void main() if(x==1)
{ return(1);
int a,fact; else
clrscr(); f=x*rec(x-1);
printf("Enter any Number:"); return(f);
scanf("%d",&a); }
fact=rec(a);
printf("Factorial Value is = %dn",fact);
getch();
}
Vinay Arora
CSED

43. Recursion
Vinay Arora
CSED

44. Program-20 (output)
Vinay Arora
CSED

45. Program-21
#include<stdio.h>
#include<conio.h>
void main()
{
int i;
clrscr();
for(i=0;i<=50000;i++)
printf("%dn",i);
getch();
}
Vinay Arora
CSED

46. Program-21 (output)
Vinay Arora
CSED

47. Program-22
#include<stdio.h> void val()
#include<conio.h> {
i=100;
int i=0; printf("Val's i=%dn",i);
void val(); i++;
}
void main()
{
clrscr();
printf("Main's i=%dn",i);
i++;
val();
printf("Main's i=%dn",i);
val();
getch();
}
Vinay Arora
CSED

48. Program-22 (output)
Vinay Arora
CSED

49. Program-23
#include<stdio.h>
#include<conio.h>
void main()
{
int count=5;
clrscr();
printf("Count=%dn",count);
count--;
if(count>0)
main();
else
exit();
getch();
}
Vinay Arora
CSED

50. Program-23 (output)
INFINITE LOOP
Vinay Arora
CSED

51. Program-24
#include<stdio.h> int g(int x)
#include<conio.h> {
int v=1;
int g(int); int b=3;
void main()
{ v+=x;
int i,j; return(v+x+b);
clrscr(); }
for(i=1;i<5;i++)
{
j=g(i);
printf("%dn",j);
}
getch();
}
Vinay Arora
CSED

52. Program-24 (output)
Vinay Arora
CSED

53. Program-25
#include<stdio.h>
#include<conio.h>
int x=10;
void main()
{
int x=20;
clrscr();
{
int x=30;
printf("%dn",x);
}
printf("%dn",x);
getch();
}
Vinay Arora
CSED

54. Program-25 (output)
Vinay Arora
CSED

55. Program-26
#include<stdio.h> void func()
#include<conio.h> {
int i,j,k;
void func(); i=j=k=0;
void main()
{ i++;j++;k++;
clrscr(); printf("%d%d%dn",i,j,k);
func(); }
func();
getch();
}
Vinay Arora
CSED

56. Program-26 (output)
Vinay Arora
CSED

57. Thnx…
Vinay Arora
CSED