UMBC CMSC 201, Computer Science I, Fall 1995 Sections 0101, 0102, 0103 and Honors

Project 4 Comments

Comments:

• Do not worry about negative numbers. The user can always enter

       0/1 minus 2/3
    

  if the user wants to have a negative number. If you want to put in negative numbers, that is fine for an extra feature. In that case, you may assume that only the numerator is negative (e.g., -2/3).

• The function StringToInteger has the very convenient feature that it can handle leading and trailing spaces with no problems. For example, StringToInteger(" 23 ") will correctly return the integer value 23.

• Several people have encountered this problem: when you use printf to print out a debugging statement, you must print a string with \n at the end. The reason is this. The operating system doesn't actually draw the string on your screen until a \n is received. The printed string sits in a "buffer" until a \n gets printed. If in the meantime your program crashes, the string never gets printed. So, the problem is that you end up thinking the program crashed in the wrong place. Here's an example:

        printf("Trying StringToInteger...\n") ;
        n = StringToInteger("17") ;
  
        /* This print statement has no \n */
        printf("Did the new function work?") ;
  
        /* The program dies here from division by zero */
        x = 0 ;
        n = 17 / x ;
    

  In this example, you might think that the program crashed using StringToInteger because, "Did the new function work?" never appeared on the screen. That is not the case.