goto statement problem. reply fast.

try this...

void main()
{
    float rs,p;
    char z='y';
    clrscr();
  while(z=='y')
   {
    printf("\nEnter the value rs");
    scanf("%f",&rs);
    p=rs*100;
    printf("\n\npaisa =%2.f ",p);
    printf("\n do you want to access operation once again? press y/n");
    scanf("%c",z); 
    }
getch();
}

try this...

void main()
{
    float rs,p;
    char z='y';
    clrscr();
  while(z=='y')
   {
    printf("\nEnter the value rs");
    scanf("%f",&rs);
    p=rs*100;
    printf("\n\npaisa =%2.f ",p);
    printf("\n do you want to access operation once again? press y/n");
    scanf("%c",z); 
    }
getch();
}

void main()
{
    float rs,p;
    char z;
    clrscr();
rep : ;
    printf("\nEnter the value rs");
    scanf("%f",&rs);
    p=rs*100;
    printf("\n\npaisa =%2.f ",p);
    printf("\n do you want to access operation once again? press y/n");
    if(z=='y') /* i have check this also by if(z=='y') but its not working. */
        goto  rep;
getch();

Have a look at the following tutorial:

C goto statement