Lab 1 Solution

(click on "Lab Ch01" above and scroll down to upload, attach and submit file DDHH_L1_Lastname.cpp)




The first few labs transition into C++. The concepts should be review. C++ may be new to you. If you have not written a program for a while, have not used C/C++, are a bit "rusty", or have not set up a development environment (devcpp, code::blocks, Visual Studio, GCC, Xcode, etc.) these first few labs ease you back into the game.




We spend some time getting familiar with C++ syntax. If C++ is new to you, it may look odd at first. The concepts should be familiar: input, processing, output. Ask for user input with a prompt, get input, process the input, provide output. The skills needed for this lab are in the first few chapters of our textbook. Since you have programmed before, your main task for this lab is to learn how to do things in C++. Hopefully, you have done code like this before, perhaps in Python, Java, BASIC, C/C++, C#, Swift or whatever.




C++ is a strongly typed language. Whereas Python has numeric types int and float, C++ has: char, short, int, long, float, double, long double, etc. There are important consequences of using, mixing, and matching different types. One goal of this lab is to observe the use of multiple types. C++ can "cast" from one type to another. Incorrect casting can result in undesired results. Use the types specified in bold. Use casting as needed. Use the modern style of cast: static_cast < new_type (value). For example: static_cast < double (percent).




Write one program that helps solve restaurant related questions. These are as easy as abc: advice, BMI (body mass index), check (payment due with tax and tip.). The options are:




1) Advice: give advice on what to order at the restaurant. Keep it short, just one line will do. You decide on the advice.




2) Body Mass Index (BMI) – write code that computes BMI. The formula is:

BMI = (weight in pounds / (height in inches x height in inches) ) x 703

a) Ask for and get the user's data. Use data type int for both.

b) Calculate the BMI. For the result, use data type double.

c) Display the BMI.




3) Check - write code that calculates a restaurant check given cost of food and tip percentage:

a) Ask for and get the cost of food. Use data type double.

b) Ask for and get the tip percentage. Use data type double.

c) Internally, declare the tax rate: const double TAX_RATE = 0.0825. Do not ask for tax rate.

d) Compute the total bill, using the: food cost, TAX_RATE and tip percentage.

What should the tip be? Based on food cost? Food cost and tax? You decide; provide comments.

e) Print out the total bill.




Test this. If you stop here, you have earned up to 10 points max.




4) Combine the three parts above into a menu. Prompt the user for whether they want to perform:




Options (enter one letter): a)dvice b)mi c)heck q)uit:

a) Ask for and get the option desired. Use data type char.

b) if option a, provide advice; if option b, calculate BMI; if option c, compute check

Test this. If you stop here, you have earned up to 18 points max.




5) Loop the program, Add option q to quit. Loop until the user enters q to quit.

a) Enter a loop.

b) Ask for and get the option desired.

c) if invalid option, display error message and continue

d) if q, then quit

 

Test this. If you stop here, you have earned up to 20 points max.




Extra credit:

a) ignore the option’s case (uppercase or lowercase). Hint: use toupper() or tolower()

b) format the output of the bill as: $xx.xx. format the BMI as xx.xx. (display 2 decimal places)

c) ask for height in feet and inches instead of just inches; convert into inches.

Test this. If you stop here, you have earned up to 22 points max. This is the most possible points.




Example code for main loop:




while (true) {

cout<<"Options (enter one letter): a)dvice b)mi c)heck q)uit: ";

char option=' ';

cin option;

if (option=='a') {

// provide advice.

}

else if (option=='b') {

// compute and display the BMI

}

else if (option=='c') {

// compute and display check amount

}

else if (option=='q')

break;

else

// invalid option entered, display an error message

}




Use appropriate commenting and indenting style. See information on programming style under the 'Dev C++ Compiler' button. Attach a single .cpp file on the Blackboard assignment link. This can be done in about 30 to 40 lines of code. Use the file naming convention: TT10_L1_Lastname.cpp.




Provide a comment block which contains this information at the top of all labs for this class:

// Author: Sam Houston; Course: COSC 1337 Spring 2019 TT10; Instructor: Thayer

// Lab 1: Provide menu-driven option loop that provides restaurant advice; BMI; check amount or quits the loop.




<code goes here




To verify you have tested your code, copy and paste the output from the cmd.exe display screen into your source code in a comment block at the very bottom. See instructions on how to do this under Assignments, Labs 1 - 3. “Test and Verify: How To Copy Program Output Into Source Code”




/* Example test output. This goes at the bottom.

This program helps with restaurant questions.




Options (enter one letter): a)dvice b)mi c)heck q)uit: a

The chicken soup is excellent. Avoid the mashed turnips.




Options (enter one letter): a)dvice b)mi c)heck q)uit: b

Weight in pounds? 155

Height in inches? 62

BMI is: 28.35




Options (enter one letter): a)dvice b)mi c)heck q)uit: c

Food cost? 20.00

Tip percent (10 = 10%)? 10

Restaurant bill is: $23.65




Options (enter one letter): a)dvice b)mi c)heck q)uit: d

Option d is invalid. Please try again.




Options (enter one letter): a)dvice b)mi c)heck q)uit: q

Good-bye!

*/

You can use the sample C++ code above for looping and decisions. For more help, see chapter 4 on Making Decisions and chapter 5 on Looping. We will go into more detail on decisions and looping later.