Introduction

This lab will familiarize you with the use of Turbo C for Windows on the UMD PC network. In this lab you will create a project, create files, compile, debug and run a program.

Using the Lab

If you are not in the lab for your scheduled lab time you will need to give your ID to a lab consultant to obtain a machine. Please check to see if someone is using the machine you were given. If so, look for a different machine. If the lab is full during your scheduled lab time, please ask your TA or the consultant to announce that it is a scheduled lab time for your class only.

Finding and Starting Turbo C

From the toolbar at the bottom of the Windows 95 desktop select the Start button. This will pop up a menu. Now from the menu select Programs - Specialized Academic Software - Programming languages - C++ - Turbo C++ which brings up the Turbo C software. Your TA will help you with this during your first lab section.

Writing Your Program

• Creating a program file. Choose File-New from the menu to create a new file. Save this new file as your lab1 C source file. This is done by selecting File-Save. Once selected, a file dialog is displayed. Enter the filename (for example, lab1.c) you want the program file to have. Select the destination drive as A:, so the file is saved on your floppy disk and choose OK.

• Enter the program. At the end of this document there is a simple program which attempts to guess a number you are thinking of that is between 1 and 100. Type this program into the file exactly as shown, except that you insert your name, section number, and date as indicated. Save the file often and save the file a final time once you are done entering it. To do this click on the File-Save menu item.

Compiling the Program

Select the Project-Compile command from the menu to compile the program. A Compile status dialog box appears on the screen, giving information about the compilation. If no errors occur, the message ``Successfully completed'' is displayed in the Status dialog box. Choose OK to put the dialog box away.

If an error (compile-time errors) occurred during compilation, compilation stops, the compile status dialog goes away automatically, an error message appears on the status bar, and the line that cause the error is highlighted in the edit window. Edit your C file to correct the errors, save it, and then attempt to compile your program again.

Running the Program

To run the program select Debug-Run menu item. Follow the instructions and see how long the program needs to guess your number.

If an error (Run-time error) occurs while you execute your program, note the name of the run-time error. To find out more about this error, go to the Search option under the Help menu (or press the F1 key). Here you could submit the name of the error to be searched for. Under the heading Error and Warning Messages is a complete listing of all Turbo C++ error (both compile-time and run-time) messages. If you neither got an error nor your program output looks like the one shown above then there are some errors in your program which the compiler did not detect.

These must be corrected before going further. Once the program is working try to figure out how many guesses it will take the computer to find the number you are thinking of. Change the line of the program

  highest = 100;

  highest = 1000;

Printing Your Program

• Printing your program. Select the window that contains your program. Choose File-Print from the menu to print the program source.
• Printing your program output. To print your output, select the window that contains your output. In the upper left corner is a rectangular window icon. Select it and hold down the mouse button until a menu appears, then select Print.

What To Hand In

Hand in the following items:

• Printout of the code you typed.
• Copies of the output showing the computer guessing your number several times.
• What you think the maximum number of guesses the computer needs to get your number between 1 and 100.

The Program

/*
 * Your Name
 * CS 1621 Section ?
 * Today's date
 * Lab #1
 */

#include <stdio.h>
 
int main() {
  int lowest;
  int highest;
  int found;
  int guess;
  int guesscount;
  char answer;

  lowest = 1;
  highest = 100;

  printf("Think of a number between %d and %d",lowest,highest);
  printf(" and I will try to guess it.\n");

  printf("Type return when you are ready.\n");
  scanf("%c",&answer);

  found = 0;
  guesscount = 0;
  while (!found) {
    guess = (lowest + highest) / 2;
    printf("Is the number %d (y/n)? ", guess);
    guesscount++;
    fflush(stdin);
    scanf("%c",&answer);
    if ((answer == 'Y') || (answer == 'y')) {
      found = 1;
      printf("\nHooray!  Got it in %d guesses!\n",guesscount);
    }
    else {
      printf("Is the number you are thinking of higher (h) or lower (l)? ");
      fflush(stdin);
      scanf("%c",&answer);
      if ((answer == 'H') || (answer == 'h'))
        lowest = guess + 1;
      else
        highest = guess - 1;
    }
  }
}