Lab 23

File Input/Output

CS211 Lab Policy:

• This lab exercise will not be graded.
• Submit as much as you have completed before the end of the lab period in which it is assigned.
• If you do not finish this lab work, it is to your advantage to finish it outside of class. Please re-submit your finished work to the course web site.
• You may receive help from anyone in completing this lab.
• You may not submit another student's code as part of your lab.

Instructions:

Create one program named Lab23 that includes code that implements the tasks specified below. Save your program in a file named Lab23.m.

1. Begin your Lab23() function by clearing the command window.
    
2. Prompt and get from the user a positive integer value that represents the size of a "Pascal triangle." A "Pascal triangle" is a series of numbers in the shape of a triangle where each value in the interior of the triangle is calculated by summing the two values "above it". All numbers on the "edges" are equal to one. Several example are shown below.
    
3. Prompt for and get from the user a string of characters that specifies a file name. The file name should have no extension.
    
4. Using the MATLAB statement below, create a Pascal triangle of the user specified size.
   
       Triangle = abs(pascal(User_size, 1));
    
5. Now create 3 different printouts of the Pascal triangle and store each printout in a distinct file.
   1. The first file should be named with the user specified name appended with "_left.txt". The numbers of the triangle should be left justified to form a lower triangular matrix. (See examples below.)
       
   2. The second file should be named with the user specified name appended with "_centered.txt". The numbers of the triangle should be centered to form a triangle with its top value in the middle of the page. (See examples below.)
       
   3. The third file should be named with the user specified name appended with "_right.txt". The numbers of the triangle should be right justified to form a triangle with the right side forming a vertical line. (See examples below.)

Some examples:

• If the user entered 6 for the Pascal triangle size and a file name of "sam," then the following files should contain the numbers formatted as shown below:
   
  • In the file "sam_left.txt"

       1
       1     1
       1     2     1
       1     3     3     1
       1     4     6     4     1
       1     5    10    10     5     1

  • In the file "sam_centered.txt"

                           1
                        1     1
                     1     2     1
                  1     3     3     1
               1     4     6     4     1
            1     5    10    10     5     1

  • In the file "sam_right.txt"

                                             1
                                       1     1
                                 1     2     1
                           1     3     3     1
                     1     4     6     4     1
               1     5    10    10     5     1

 

• If the user entered 10 for the Pascal triangle size and a file name of "alpha," then the following files should contain the numbers formatted as shown below:
   
  • In the file "alpha_left.txt"

       1
       1     1
       1     2     1
       1     3     3     1
       1     4     6     4     1
       1     5    10    10     5     1
       1     6    15    20    15     6     1
       1     7    21    35    35    21     7     1
       1     8    28    56    70    56    28     8     1
       1     9    36    84   126   126    84    36     9     1

  • In the file "alpha_centered.txt"

                                       1
                                    1     1
                                 1     2     1
                              1     3     3     1
                           1     4     6     4     1
                        1     5    10    10     5     1
                     1     6    15    20    15     6     1
                  1     7    21    35    35    21     7     1
               1     8    28    56    70    56    28     8     1
            1     9    36    84   126   126    84    36     9     1

  • In the file "alpha_right.txt"

                                                                     1
                                                               1     1
                                                         1     2     1
                                                   1     3     3     1
                                             1     4     6     4     1
                                       1     5    10    10     5     1
                                 1     6    15    20    15     6     1
                           1     7    21    35    35    21     7     1
                     1     8    28    56    70    56    28     8     1
               1     9    36    84   126   126    84    36     9     1

Hints:

• There are several ways you can form the file names. Some possibilities include:
  • Use strcat(). For example, Full_name = strcat(My_file_name, '_right.txt')
  • Use [ ]. For example, Full_name = [My_file_name '_right.txt']
  • Use sprintf(). For example, Full_name = sprintf('%s_right.txt', My_file_name);
     
• There are several ways you can write a series of blanks. Use the MATLAB help system to look up the details on the following methods. Each example below prints 10 blanks.
  • fprintf('%s', blanks(10));
  • for j = 1:10; fprintf(' '); end;
  • fprintf('%*s', 10, ' ');
     
• It is recommended that you print your output to the screen as you debug your code. After your code generates the correctly formatted output, modify the fprintf() function calls to write the output to appropriate files.
   
• If you use '\n' in your code to begin a new line in your txt files, and you open the txt files with notepad.exe, the file will not display correctly. You have two options:
  • When you examine the files, open them with wordpad.exe (or Microsoft Word).
  • Use '\r\n' in your code to begin a new line.

Turn-in:

Submit your Lab23.m file and one example of each output text file.