ECE 0301: ECE Problem Solving With C++

1.   Download the starter code from Canvas for problem02

2.   Open VSCode and choose “File” > “Open Folder” and navigate into the problem02 folder (the same location as the CMakeLists.txt) and click “Open”/ “Select Folder” .

3.   Open problem02.cpp in the VSCode editor, and create a program that defines the

following values for resistance (R) and voltage (V). We’re using R and V to indicate the  values, however it is recommended that you do not use these single-letter variables in your program:

R = 1 kΩ = 1000 Ω

V = 5 V

Use Ohm’s law to calculate the current (I = V/R), and output the current value to stdout in the format shown below:

If R = 1000 Ohms and V = 5 Volts, then I = 0.005 Amps

4.   Test your program by running it in debug mode in VSCode. Similar to the first programming problem, follow the steps below:

a.   With your .cpp file open in the VSCode editor, open the command palette

(Ctrl+Shift+P) and run CMake: Configure. If prompted to select a kit choose the  same as you did for the first programming problem, and if prompted to select a variant choose “Debug” .

b.   Open the Command Palette again (Ctrl-Shift-P) and select CMake: Build. Check for build errors in the Problems tab.

i.   Note that there is a bonus option for this problem, so when you run a build you may be prompted to choose the build target. Choose problem02 for now.

c.   Open the Command Palette again (Ctrl-Shift-P) and select CMake: Debug to run your program in debug mode.

d.   As you make edits to your program and you want to re-run it, just run CMake:

Debug again. You do not need to re-run CMake: Configure every time, only when you first open a folder in VSCode, and CMake: Debug runs a build automatically before debugging if anything in the project has changed.

5.   Test your Ohm’s law calculation by changing the value of the voltage variable and

confirm that your current output is what you expect. Test at least the following values: 1 V, 2 V, 100 V

6.   Modify your program to take user input of the voltage value using cin. Keep your

resistance value fixed at 1 kΩ, and prompt the user to input a voltage with the prompt “Enter voltage:” . Your program should still calculate and output the current, now using the user-specified voltage.

7.   Follow the instructions below to test your program with user input:

a.   You previously practiced running an executable from the terminal, for example: ./problem02

When running a program from the Terminal that takes input with cin, you can enter inputs via the Terminal. This is a fine way to test, but again it is useful to be able to run debugging as programs get more complex, as described next.

b.   To allow user input when running CMake: Debug in VSCode, we need to set up   some configuration parameters. To do this, we’ll create a launch.json file, which allows us to configure parameters on “ launch” (running our executable). Follow  the steps below to set up your launch file:

i.   Ensure you have opened your problem02 folder using “Open Folder” in VSCode, and that you have the problem02.cpp file open in the VSCode  editor

ii.   Click on the Debug icon in the left sidebar, and then click “create a launch.json file” below the Run and Debug button:

If a menu appears prompting you to select from options for the

launch.json file and C++ is not listed, ensure that you first have the .cpp file open in the editor, and then try again clicking “create a launch.json  file” .

iii.   When the launch.json file opens in the editor, click “Add Configuration …” in the bottom right and select C/C++ launch

iv.   Your launch file should now look similar to the following. Although it may be slightly different depending on your operating system, the important   parts for now are the “program”, “cwd”, and “externalConsole”:

v.   Edit the string next to program to read

"${command:cmake.launchTargetPath}"

This will ensure that the program is built and run using CMake, similar to running CMake: Debug.

vi.   Edit the string next to “cwd” to read "${workspaceFolder}"

vii.   To enable using a terminal for user input, change the Boolean for “externalConsole” to true.

viii.   Save your launch.json file, then run and debug your program by clicking  the green play button “Start Debugging” that appears next to the launch task at the top of the left sidebar:

ix. IMPORTANT: When using a launch file, you should always debug using the “Start Debugging” button instead of running CMake: Debug.

x.   Now when you run debugging, an external console will appear where you can enter user input. Close the terminal once your program exits.