Homework 2, Multiple Files.

Short Description:

Goals

• Created header and implementation files for a personal library.
• Written a test driver for this library
• Used this library in a program.

Formal Description

1. Begin by creating the header file Hex.h
   • Edit the file Hex.h.
   • Add the guards
     • Either #pragma once
     • Or

       #ifndef HEX
       #define HEX
       
       #endif 

     • BUT NOT BOTH
   • You will need the string library so include that
     • #include <string>
   • Declare a string constant HEX_DIGITS
     • const std::string HEX_DIGITS {"0123456789ABCDEF"};
     • Since this file is intended to be included in other code, we do not want to have using namespace std;
       • That would force our clients to use the standard namespace.
       • And that is not polite.
     • So we must use std::string anywhere we want a string.
   • Declare two functions

     • int HexDigitToInt(char digit);
       char IntDigitToHex(int digit); 

   • Save this file for now, we will add further functions later.
2. Create the implementation file Hex.cpp
   • Edit the file Hex.cpp
   • Include iostream
   • Include Hex.h
     • #include "Hex.h"
     • Since this is in the local directory, use "" not angle bracket.s
   • Add using namespace std;
     • using is only acceptable in a stand alone compile unit.
     • Ie the code is compiled and turned into an object file.
     • This is a stand alone compile unit, we will produce Hex.o
     • So we can include the statement.
     • And we will not have to use std::string everywhere.
   • Implement HexDigitToInt
     • Create a variable that will be the return value, initialize this to be -1
     • Search for the digit in HEX_DIGITS using the string find function.
     • If the digit is found, set the return value to be the position of that digit.
     • Return the return value.
   • Implement IntDigitToHex
     • Set a return value to be a space.
     • If the int digit is between 0 and the size of the HEX_DIGITS string set the return value to be that the character at that index position.
     • Return the return value.
   • Save the file, we will return to it later.
3. Modify a Makefile to compile this.
   • I hardly ever build Makefiles from scratch.
   • Start with this Makefile
   • Modify the OBJS = line
     • Make it OBJS = Hex.o
     • This is temporary, we will change this later.
   • Add a line below all: ${OBJS}

     • all: ${OBJS}
       
       Hex.o: Hex.h 

     • This tells make that if Hex.h changes, it should recompile Hex.o.
     • This is standard
     • Every time you have a header file associated with an implementation file, you will want this line.
   • Save the file.
   • Type make
     • This should build Hex.o
     • If there are errors, fix them.
4. Write a simple test driver in hexTest.cpp
   • Edit the file hexTest.cpp
   • Include iostream and string.
   • Include Hex.h, remember this will need quotes not angle brackets.
   • In main
     • Loop from 0 to 15
       • Convert the LCV to a Hex digit.
       • Convert it back to an integer.
       • Make sure the LCV and the integer returned are the same.
   • Edit the Makefile
     • Change OBJS = Hex.o
       • It should be OBJS = hexTest
     • Add a line below all: ${OBJS}
       • hexTest: Hex.o
       • This tells make to link Hex.o with hexTest when building the final executable.
     • Compile by typing make
       • Remove all errors.
   • Run the code.
5. Add the function IntToHex to the files.
   • Add the function prototype to the Hex.h file.
     • std::string IntToHex(int number)
   • Implement the function in Hex.cpp

     • Initialize the return string to be blank.
       If the number is negative, note this and make the number positive.
       If the number is 0, 
          set the return value to be "0"
       else
          while the number is greater than 0
             digit = number % 16
             add the digit as a hex digit to the front of the number. (use IntDigitToHex)
             number = number / 16
       If the original number was negative
          add a negative sign to the string
       return the string.
                      

   • Edit hexTest.cpp
     • Add a second loop, say -40 to 40
       • Convert the LCV to hex and print out the results.
   • Compile, run, and check the results.
   • Fix any errors.
6. Add the function HexToInt to the files
   • Add the function prototype to the header file.
     • int HexToInt(std::string number)
   • Implement this function in the implementation file.
     • Deal with a negative sign as the first character
     • Skip a '+' as the first character
     • Using Horner's method

       set value to 0
       For i = the first valid digit to the last valid digit
           value = value * 16 + the the value of number[i]
       

   • Modify the test driver
     • In the second loop, convert the hex number back to an integer.
       • Check to see if the lcv is equal to this new value.
     • You should also test the special cases of
       • Hex 0
       • Hex +123
7. Build simple calculator.
   • Create a separate program, calc.cpp
     • Use the hex library you have just constructed.
     • Ask the user for two numbers in hex.
     • Ask the user for a simple operation (+, -, *)
     • Convert the numbers to decimal
     • Perform the computation
     • Print the result as a hex value.
   • Modify the Makefile to compile this program
     • Hint, it should look much the same as hexTest
   • Build the calculator
   • Test the calculator, removing any errors.

Required Files

Submission