2. Standard input ^
# This is my second Perl program, called p1_2.pl
# It's just a simple perl program.
# It's made on Nov. 24, 1996 by Tony Zhang.
$mystring = <STDIN>;
print ($mystring); # print a string to screen


3. Omvandla engelska mil till kilometrar och tvärtom ^
# p2_1.pl

print ("Enter the distance to be converted:\n");
$originaldist = <STDIN>;
chop ($originaldist);
$miles = $originaldist * 0.6214;
$kilometers = $originaldist * 1.609;
print ($originaldist, " kilometers = ", $miles,
" miles\n");
print ($originaldist, " miles = ", $kilometers,
" kilometers\n");


4. Exempel på if-sats
# p2_2.pl

print ("Enter a number:\n");
$number = <STDIN>;
chop ($number);
if ($number) {
print ("The number is not zero.\n");
}
print ("This is the last line of the program.\n");


5. Likhet mellan två tal
# p2_3.pl

print ("Enter a number:\n");
$number1 = <STDIN>;
chop ($number1);
print ("Enter another number:\n");
$number2 = <STDIN>;
chop ($number2);
if ($number1 == $number2) {
print ("The two numbers are equal.\n");
}
print ("This is the last line of the program.\n");


6. Exempel med if…else
# p2_4.pl

print ("Enter a number:\n");
$number1 = <STDIN>;
chop ($number1);
print ("Enter another number:\n");
$number2 = <STDIN>;
chop ($number2);
if ($number1 == $number2) {
print ("The two numbers are equal.\n");
} else {
print ("The two numbers are not equal.\n");
}
print ("This is the last line of the program.\n");


7. If…elsif…else
# p2_5.pl

print ("Enter a number:\n");
$number1 = <STDIN>;
chop ($number1);
print ("Enter another number:\n");
$number2 = <STDIN>;
chop ($number2);
if ($number1 == $number2) {
print ("The two numbers are equal.\n");
} elsif ($number1 == $number2 + 1) {
print ("The first number is greater by one.\n");
} elsif ($number1 + 1 == $number2) {
print ("The second number is greater by one.\n");
} else {
print ("The two numbers are not equal.\n");
}
print ("This is the last line of the program.\n");



8. Exempel med while
# p2_6.pl

$done = 0;
$count = 1;
print ("This line is printed before the loop starts.\n");
while ($done == 0) {
print ("The value of count is ", $count, "\n");
if ($count == 3) {
$done = 1;
}
$count = $count + 1;
}
print ("End of loop.\n");




9. Exempel med until
# p2_7.pl

print ("What is 17 plus 26?\n");
$correct_answer = 43; # the correct answer
$input_answer = <STDIN>;
chop ($input_answer);
until ($input_answer == $correct_answer) {
print ("Wrong! Keep trying!\n");
$input_answer = <STDIN>;
chop ($input_answer);
}
print ("You've got it!\n");


10. Omvandla mellan versaler och gemener
# p3_4.pl

print ("Enter a line of input:\n");
$inputline = <STDIN>;
print ("uppercase: \U$inputline\E\n");
print ("lowercase: \L$inputline\E\n");
print ("as a sentence: \L\u$inputline\E\n");


11. Exempel med operatorn för potenser
# p4_1.pl

# this program asks for a number, n, and prints 2 to the
# exponent n

print ("Enter the exponent to use:\n");
$exponent = <STDIN>;
chop ($exponent);
print ("Two to the power $exponent is ",
2 ** $exponent, "\n");


12 .Inkrementering med ++
# p4_4.pl
$value = 0;
while ($value++ <= 5) {
print("value is now $value\n");
}
print("all done\n");












13 .Konkatenering av två strängar
# p4_5.pl
$resultstring = "";
print("Enter your input -- type an empty line to quit\n");
$input = <STDIN>;
chop ($input);
while ($input ne "") {
$resultstring .= $input;
$input = <STDIN>;
chop ($input);
}
print ("Here is the final string:\n");
print ("$resultstring\n");


14. Testa ett password
# p4_6.pl
print ("Enter the secret password:\n");
$password = "bluejays";
$inputline = <STDIN>;
chop ($inputline);
$outputline = $inputline eq $password ?
"Yes, that is the correct password!\n" :
"No, that is not the correct password.\n";
print ($outputline);


15. Arrayer -utskrift av en listas element
# p5_1.pl

@array = (1, "chicken", 1.23, "\"Having fun?\"", 9.33e+23);
$count = 1;
while ($count <= 5) {
print ("element $count is $array[$count-1]\n");
$count++;
}


16. Slumptalsfunktionen (med fast frö)
# p5_2.pl

# collect the random numbers
$count = 1;
while ($count <= 100) {
$randnum = int( rand(10) ) + 1;
$randtotal[$randnum] += 1;
$count++;
}

# print the total of each number
$count = 1;
print ("Total for each number:\n");
while ($count <= 10) {
print ("\tnumber $count: $randtotal[$count]\n");
$count++;
}

17. En kort sätt att skriva in en heltal i en följd till en array
# p5_3.pl

print ("Enter the start number:\n");
$start = <STDIN>;
chop ($start);
print ("Enter the end number:\n");
$end = <STDIN>;
chop ($end);
@list = ($start..$end);
$count = 0;
print ("Here is the list:\n");
while ($list[$count] != 0 || $list[$count-1] == -1 ||
$list[$count+1] == 1) {
print ("$list[$count]\n");
$count++;
}



18. Kopiering av en array till en annan
# p5_4.pl

@array1 = (14, "cheeseburger", 1.23, -7, "toad");
@array2 = @array1;
$count = 1;
while ($count <= 5) {
print("element $count: $array1[$count-1] ");
print("$array2[$count-1]\n");
$count++;
}


19. En array tilldelas en annan array
# p5_5.pl

@innerlist = " never ";
@outerlist = ("I", @innerlist, "fail!\n");
print @outerlist;


20. Utskrift av en array element för element
# p5_6.pl

@array = (14, "cheeseburger", 1.23, -7, "toad");
$count = 1;
while ($count <= @array) {
print("element $count: $array[$count-1]\n");
$count++;
}






21. Array slices
# p5_7.pl

@array = (1, 2, 3, 4);
@subarray = @array[1,2];
print ("The first element of subarray is $subarray[0]\n");
print ("The second element of subarray is $subarray[1]\n");


22. Inläsning från STDIN i array
# p5_12.pl

@array = <STDIN>;
print (@array);


23. Sortering av en array i omvänd ordning
# p5_13.pl

@input = <STDIN>;
@input = reverse (sort (@input));
print (@input);


24. Innehållet i en array bakas ihop till en sträng
# p5_14.pl

@input = <STDIN>;
chop (@input);
$string = join(" ", @input);
print ("$string\n");


25. Ett ordräkningsprogram
# p5_15.pl

$wordcount = 0;
$line = <STDIN>;
while ($line ne "") {
chop ($line);
@array = split(/ /, $line);
$wordcount += @array;
$line = <STDIN>;
}
print ("Total number of words: $wordcount\n");


26. Ett program som läser textrader från en fil och skriver ut dem
# p6_1.pl

if (open(MYFILE, "file1")) {
$line = <MYFILE>;
while ($line ne "") {
print ($line);
$line = <MYFILE>;
}
}
27. die vid försök att öppna fil
# p6_2.pl

unless (open(MYFILE, "file1")) {
die ("cannot open input file file1\n");
}

# if the program gets this far, the file was
# opened successfully
$line = <MYFILE>;
while ($line ne "") {
print ($line);
$line = <MYFILE>;
}


28. Inläsning av fil i array
# p6_3.pl

unless (open(MYFILE, "file1")) {
die ("cannot open input file file1\n");
}
@input = <MYFILE>;
print (@input);


29. En fils innehåll kopieras till en annan fil
# p6_4.pl

unless (open(INFILE, "file1")) {
die ("cannot open input file file1\n");
}
unless (open(OUTFILE, ">outfile")) {
die ("cannot open output file outfile\n");
}
$line = <INFILE>;
while ($line ne "") {
print OUTFILE ($line);
$line = <INFILE>;
}

















30. Två filer skrivs ut växelvis
# p6_5.pl

open (INFILE1, "merge1") ||
die ("Cannot open input file merge1\n");
open (INFILE2, "merge2") ||
die ("Cannot open input file merge2\n");
$line1 = <INFILE1>;
$line2 = <INFILE2>;
while ($line1 ne "" || $line2 ne "") {
if ($line1 ne "") {
print ($line1);
$line1 = <INFILE1>;
}
if ($line2 ne "") {
print ($line2);
$line2 = <INFILE2>;
}
}

31. Standard error file (vanligtvis skärmen)
# p6_6.pl

open(MYFILE, "file1") ||
die ("Unable to open input file file1\n");
print STDERR ("File file1 opened successfully.\n");
$line = <MYFILE>;
while ($line ne "") {
chop ($line);
print ("\U$line\E\n");
$line = <MYFILE>;
}


32. Ett program som testar om filen finns innan den öppnas för skrivning
# p6_8.pl

unless (open(INFILE, "infile")) {
die ("Input file infile cannot be opened.\n");
}
if (-e "outfile") {
die ("Output file outfile already exists.\n");
}
unless (open(OUTFILE, ">outfile")) {
die ("Output file outfile cannot be opened.\n");
}
$line = <INFILE>;
while ($line ne "") {
chop ($line);
print OUTFILE ("\U$line\E\n");
$line = <INFILE>;
}





33. Mönstermatchning
# p7_1.pl

print ("Ask me a question politely:\n");
$question = <STDIN>;
if ($question =~ /please/) {
print ("Thank you for being polite!\n");
} else {
print ("That was not very polite!\n");
}


34. Ordräkning med hantering av multipla mellanslag
# p7_6.pl

$thecount = 0;
print ("Enter the input here:\n");
$line = <STDIN>;
while ($line ne "") {
if ($line =~ /\bthe\b/) {
$thecount++;
}
$line = <STDIN>;
}
print ("Number of lines containing 'the': $thecount\n");
# p7_7.pl

print ("Enter the search pattern:\n");
$pattern = <STDIN>;
chop ($pattern);
$filename = $ARGV[0];
$linenum = $matchcount = 0;
print ("Matches found:\n");
while ($line = <>) {
$linenum += 1;
if ($line =~ /$pattern/) {
print ("$filename, line $linenum\n");
@words = split(/$pattern/, $line);
$matchcount += @words - 1;
}
if (eof) {
$linenum = 0;
$filename = $ARGV[0];
}
}
if ($matchcount == 0) {
print ("No matches found.\n");
} else {
print ("Total number of matches: $matchcount\n");
}