122 Lab week 4

Labs Start On the Hour

Please arrive at 026 Kla early enough to be seated and do the following:

• start FireFox, login to our Blackboard course site, open Schedule > Class Calendar
• in the calendar, click the link for the lab outline for the week
• start SSH, connect to shell.uoregon.edu, & open a File Transfer window
• start Visual C++ & open a project

If you arrive late, your lab instructor will not be able to take time away from the other students to fill you in on what you missed.

Lab Exercises

1. Displaying time in digital format (hh:mm:ss). The following is a modified version of the program on p. 44-45 of [Liang]. It prompts the user for a number of seconds 0 <= sec < 86400 and then displays the time represented by that number in digital format:
   

   /* displayTime.cpp
   
      There are 86,400 sec. in a 24-hr day, where 0 (midnight) is 00:00:00
      and 86,399 is 23:59:59.
      The following program prompts the user for a number of seconds 
      0 <= sec < 86400 and then displays the time represented by that 
      number in digital format. It is a modified version of the program 
      on p. 44-45 of [Liang]. 
   
      Exercise: modify to display leading zeros when necessary.
   */
   
   #include 
   using namespace std;
   
   const int SEC_PER_HR = 3600;
   
   int main(){
     int sec;                       //user input in seconds
     int hrs, min, remainingSec;    //computed values
   
     //prompt and read seconds
     cout << "enter seconds [0 .. 86400): ";
     cin >> sec;
   
     //echo input
     cout << sec << " seconds in digital time format is ";
     //calculate hrs and adjust sec
     hrs = sec  / SEC_PER_HR;
     sec = sec % SEC_PER_HR; 
   
     //calculate min and adjust sec
     min = sec  / 60;
     sec = sec % 60; 
   	
     //display time represented by user input
     cout << hrs << ":" << min << ":" << sec 
   	      << endl << endl;
   
     return 0;
   }
   



2. Open a project in Visual C++, select Project > Add New Item > Code > c++ file, then name the file displayTime.cpp. Copy the above c++ code from the browser window, paste it into displayTime.cpp and save. Compile and test the program.
   
   Problem: If you enter 1, this is the output:
   
              1 seconds in digital time format is 0:0:1


3. Programming exercise: modify the program to meet this I/O spec:
   
              1 seconds in digital time format is 00:00:01


4. Programming exercise: Note that the "1 seconds" is not grammatically correct. Modify the program to meet this I/O spec:
   
              1 second in digital time format is 00:00:01
   
   Programming Tip: Your lab instructor will explain this conditional operator (p. 86), which can be used for an elegant solution to this problem:
   
               cout << num
                 << ((num % 2 == 0) ? " is even" : "is odd");

/etc

Micro Labs on Campus: In addition to 026 Kla, Visual C++ 2005 Express Edition is installed in 013 Kla and 101 Mck, but it is not installed in other micro labs on campus.

Saving your Lab Work: The My Documents folder on the PCs in 026 Kla is cleared periodically. If you want to save a copy of your lab work, use SSH's File Transfer window to upload your files and/or folders to your shell.uoregon.edu account. Or bring a USB drive with you to your lab and keep your /110 folder stored on that drive.

122 IT Applications/DuckWare CD: Apart from Visual C++, alll the software applications we use in the lab (SSH, FireFox, Fugu, ...) is on the DuckWare CD, and can be installed on your personal computer. The DuckWare CD is available from MicroHelp, 151 McKenzie. See also: OS X applications and Parallels Desktop.

The 122 Learning Environment

It's important that you are able to follow along as the instructor presents material. If you cannot hear or understand what is being said, please raise your hand and say (polite always works) that you are having difficulty following the presentation. The lab instructor will appreciate your assistance.

Also, please keep in mind that your responsibility is to pay attention and follow the instructor's directions. In particular, you should not be reading email, surfing the web, visiting with other students, etc., during the lab. Save those activities for after the lab.