#include <stdio.h>
int main (void)
{
  float length,width;

printf("Enter the length of the rectangle;\n");
while (scanf("%f", &length)==1)
{
      printf("Length = %0.2f;\n",length);
      printf("enter its width;\n");
      if (scanf("%f",&width)!= 1)
          break;
      printf("Width = %0.2f;\n",width);
      printf("Area = %0.2f;\n",length * width);
      printf("Enter the length of the rectangle;\n");
    }
      printf("done.\n");
      return 0;
}

Enter the length of the rectangle;
done.