Homework Assignment 5 Solution

This assignment deals with characters and strings, as described in Chapter 7. Assignment 6 may be posted before Assignment 5 is due, so finishing Assignment 5 early may be advantageous.




Problem 1 (50 points)




The Python programming language provides the programmer with a variety of string manipulation methods (functions). For this assignment, you'll implement two of those functions as CUSP subroutines.




The first of these Python methods is swapcase() . This function expects a string as an argument and returns a copy of the original string but with a lower case letters converted to upper case, and all upper case letters converted to lower case. Characters that are not letters remain unchanged. Here is an example of the function in action:

test = "lEArN pYtHOn iN 30 YeaRS!"
result = test.swapcase()
print(result)
LeaRn PyThoN In 30 yEArs!




The task for you is to write a subroutine in CUSP that does what swapcase() does. Your subroutine should expect the following parameters to be pushed on the stack by the calling procedure in this order:




The starting address of the original string will be pushed first on the stack




The number of characters in that string will be pushed next The starting address of the converted string will be pushed last




Name your subroutine swapcase. Your subroutine should create a new string as described above and place the new string in memory starting at the address given in the last parameter pushed on the stack. Note that the original string should not be altered in any way by your subroutine.




As with the previous homework assignment, you’ll want to write a “main program” to serve as the calling procedure to test your subroutine. Have your calling procedure load into memory at $000, and have your swapcase subroutine load into memory at $020. Put your calling procedure and your subroutine in a text file named hw5p1.csp. Put the object code in a file named hw5p1.obj.

Problem 2 (50 points)




The second of the Python string methods is title(). This function expects a string as an argument and returns a copy of the original string but with the first letter in each word is changed to upper case and with all other letters changed to lower case. Characters that are not letters remain unchanged. Here is an example of the function in action:

test = "lEArN pYtHOn iN 30 YeaRS!"
result = test.title()
print(result)
Learn Python In 30 Years!




The task for you is to write a subroutine in CUSP that does what title() does. Your subroutine should expect the following parameters to be pushed on the stack by the calling procedure in this order:




The starting address of the original string will be pushed first on the stack




The number of characters in that string will be pushed next The starting address of the converted string will be pushed last




Name your subroutine title. Your subroutine should create a new string as described above and place the new string in memory starting at the address given in the last parameter pushed on the stack. Note that the original string should not be altered in any way by your subroutine. Also note that in Python, the title() method considers apostrophes to be word boundaries. Ignore that fact, so your subroutine should only treat spaces as word boundaries, not apostrophes.




Once again, you’ll want to write a “main program” to serve as the calling procedure to test your subroutine. Have your calling procedure load into memory at $000, and have your title subroutine load into memory at $020. Put your calling procedure and your subroutine in a text file named hw5p2.csp. Put the object code in a file named hw5p2.obj.




Include all four files (the two .csp files and the two .obj files) in your submission through Canvas.