Pointer Operations in C programming

1)      Address of any variable can be assigned to a pointer variable. E.g.

        p=&a;   q=&b ;

              where p & q are pointer variables and a & b are simple variables.

2)      Content of one Pointer can be assigned to other pointer provided they point to same data type. E.g.

           int *p, *q;

            p=q;

3)      Integer data can added to or subtracted from pointer variables.

        E.g. int *p;

                p+1;

4)      One pointer can be subtracted from other pointer provided they point to elements of same array. E.g.

         int a[3],*pf,*pl;

           pf=a;

           pl=a+2;

      printf(“%p”,pl-pf);

5)      There is no sense in assigning an integer to a pointer variable.

6)      Pointer variable can not be multiplied and added.

7)      Null value can be assigned to a pointer variable.

Passing pointer to a function

       

  Write a program to covert upper case letter into lower and vice versa using call by reference.

void conversion(char *); //function prototypes

void main()

 {

  char input;

  clrscr();

  printf("Enter Character of Ur choice\n");

  scanf("%c",&input);

  conversion(&input);

  printf("\nThe corresponding character is\t%c",input);

  getch();

}

void conversion(char *c)

  {

  if(*c>=97 && *c<=122)

     *c=*c-32;

  else if(*c>=65 && *c<=90)

    *c=*c+32;

  }