Programming in Perl -- Sample Test

Your name:

Your RCS userid:

Have you ever used HTML to create a webpage?

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Question 1 [20 pts]
In the space provided below, indicate what the following snippet of Perl code prints (represent a newline by <n> and assume that the -w flag is not used so no warnings will be printed):

$a1 = 1;
$var1 = "15th " + "St" . "8th " . "St";
$var2 = 2;
$var3 = "N = " . 13 x $var2;
$var4 = 'camel\n';
chomp($var4);
$var5 = chop($var4);
@a1 = (1, 2, 3, 4);
@a2 = reverse(@a1);
($var6, $var7, $var8) = @a2[0,1];

print ( "$var1\n" ); # 1
print ( "$var2\n" ); # 2
print ( "$var3\n" ); # 3
print ( "$var4\n" ); # 4
print ( "$var5\n" ); # 5
print ( "$var6\n" ); # 6
print ( "$var7\n" ); # 7
print ( "$var8\n" ); # 8
print ( "$a1[$a2[$#a1]]\n" ); # 9
print ( "${a1}[$a2[-2]]\n" ); # 10

1)

2)

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Question 2 [25 pts]

Read a series of numeric class grades from standard input into an array (assume one grade per line). You may assume all data entered is valid. After the values have been input, determine the number of A's, B's, C's, and F's based on the following scale:

Score	Grade
90-100	A
80-89	B
70-79	C
0-69	F

You should also compute the average grade for the class. Print the class average, the number of A's, the number of B's, the number of C's, and the number of F's. Each piece of information should be printed on a separate line with appropriate text labels, e.g.,

Class average : 75<newline>
Number of A's: 20<newline>
(and so forth)

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Question 3 [30 pts]
Given the following arrays:

@day_nums = (1, 2, 3, 4, 5, 6, 7); 
@day_strings = ('mon.', 'tue.', 'wed.', 'thur.', 'fri.', 'sat.', 'sun.');

(a): Assign the same values as in the first assignment above to @day_nums using the list constructor operator (..).
(b): Assign the same values as in the second assignment above to @day_strings without explicitly using either single or double quotes around the strings.

Given the following hash:

%days = (1, 'mon.', 2, 'tue.', 3, 'wed.', 4, 'thur.', 
         5, 'fri.', 6, 'sat.', 7, 'sun.');

(c): Use the arrays @day_nums and @day_strings to create a hash %days1 having the same key-value pairs as %days.
(d): Create a hash %days2 having the same key-value pairs as %days using the => operator and literals.
(e): Use the foreach control structure along with any built-in functions needed to print the values of the hash %days on separate lines.
(f): Iterate through the hash %days using the each function and print the values of the hash on separate lines with the first letter of each day capitalized.

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Question 4[25 pts]

Use the diamond operator to write a Perl script that functions as a simple more command. If a user types more.pl file1, the script should print the first $max_num_lines (say 20) lines of file1 and then prompt the user for input from standard input as follows:

(lines from file1)
Action [l or p]:

The script should continue prompting for and reading the $action until an l followed by a return or a p followed by a return is typed. If an l is entered, the script should print the next line of the file and prompt again for an action. If a p is input, the script should print the next $max_num_lines lines of file1 before prompting for an action again. This process (prompting and printing either the next line or the next $max_num_lines lines) should continue until the file's contents are exhausted.