CSE 232 Spring 2012                    Name: __________________________________

Lab Exercise #5 -- C++ Functions and Modules

A. The "make" Utility

Copy all of the files named "~cse232/Labs/lab05.*" into your account, then
perform the following experiments.

1. Use the "make" utility to control the translation of the program:

   <prompt> make -f lab05.makefile

Name the files which are created by this command, and explain what is
contained in each file:

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2. Enter the "make" command again:

   <prompt> make -f lab05.makefile   (or, "!make" to use history substitution)

What results are reported, and why?

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3. Edit your copy of "lab05.driver.cpp" and make some cosmetic change to the
source code (modify a comment or the spacing of some statement, for example).
Then, enter the "make" command again.

What files are created by this operation, and why?

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4. Edit your copy of "lab05.support.h" and make some cosmetic change to the
source code.  Then, enter the "make" command again.

What files are created by this operation, and why?

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5. What criteria is "make" using to decide whether or not to re-create a given
object code file?

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B. Scope and Lifetime

Recall that one of the attributes of an identifier is its scope (file scope or
block scope); an identifier which represents a data object also has a lifetime
associated with it (program lifetime or block lifetime).

1. Examine the contents of "lab05.driver.cpp" and complete the following chart.

   Identifier      Scope           Lifetime

   cin             ____________    ____________

   cout            ____________    ____________

   InputStatus     ____________    ____________

   RootStatus      ____________    ____________

   Root2           ____________    ____________

2. Examine the contents of "lab05.support.cpp" and complete the following chart.

   Identifier      Scope           Lifetime

   cin             ____________    ____________

   cout            ____________    ____________

   InputStatus     ____________    ____________

   Flag            ____________    ____________

   Discriminant    ____________    ____________

3. Revise "lab05.support.h" to include the declaration of "InputStatus", but
not the statement where storage is allocated.  That is, the following
statement should be moved into "lab05.support.h":

   extern int InputStatus;

However, the following statement should remain in "lab05.support.cpp":

   int InputStatus;

Use the "make" file to translate the program, then execute it and verify that
it still has the same behavior.

4. In general, it is a good idea to avoid the use of "global" variables (ones
with file scope and program lifetime) because they can be modified via an
assignment operation in any function that is part of the program.

Eliminate the global variable "InputStatus" from the program.  Then, revise
the declaration and definition of function "coefficients" so that it returns
the input status to the callng function via a "return" statement.

Use the "make" file to translate the program, then execute it and verify that
it still has the same behavior.

5. Demonstrate the final version of the program to your TA.