Function

  #include⁢stdio.h>
  void star(int n)
  {
    int i;
    for( i=1 ; i <= n ; i++ )
        printf("*");
  }
  main()
  {
    star(25);
    printf("\n");
    star(40);
    printf("\n");
    star(15);
  }

  #include⁢stdio.h>
  void circle(int r)
  {
    float a,c;
    a=3.14*r*r;
    c=2*3.14*r;
    printf("Area is %f\n",a);
    printf("Circumference is %f",c);
  }
  main()
  {
    circle(5);
  }

  #include⁢stdio.h>
  void even(int n)
  {
    int i;
    for(i=2;i<=n;i=i+2)
        printf("%d ",i);
  }
  main()
  {
    even(40);
    printf("\n");
    even(25);
    printf("\n");
    even(10);
  }

  #include⁢stdio.h>
  void display(int a,int b)
  {
    int i;
    for(i=a;i<=b;i++)
        printf("%d ",i);
  }
  main()
  {
    display(10,20);
    printf("\n");
    display(5,25);
  }

  #include⁢stdio.h>
  void interest(int p,float r,int n)
  {
    float si;
    si=p*r*n/100;
    printf("\nSimple Interest is %f",si);
  }
  main()
  {
    interest(5000,10.25,3);
    interest(25000,11.75,5);
  }

  #include⁢stdio.h>
  void  sum(int n)
  {
    int i,s=0;
    for(i=1;i<=n;i++)
        s=s+i;
    printf("sum is %d\n",s);
  }
  main()
  {
    sum(5);
  }

  #include⁢stdio.h>
  void  factorial(int n)
  {
    int i,f=1;
    for (i=1;i<=n;i++)
        f=f*i;
    printf("factorial is %d\n",f);
    }
  main()
  {
    factorial(5);
  }