Question

Help needed in Perl language program! Note : Perl Language

Rock, Paper, Scissors (also known by several other names, see http://en.wikipedia.org/wiki/Rock paper scissors) is an extremely popular hand game most often played by children. Often, it is used as a method of selection similar to flipping a coin or throwing dice to randomly select a person for some purpose. Of course, this game is not truly random since a skilled player can often recognize and exploit the non-random behavior of an opponent; for instance, if you notice that your opponent chooses Paper most frequently, you may choose Scissors (which beats Paper) most often in an effort to win Rules of the Game: The objective of Rock, Paper, Scissors is to defeat your opponent by selecting a weapon that defeats their choice under the following rules .Rock smashes (or blunts) Scissors, so Rock wins Scissors cut Paper, so Scissors win Paper covers Rock, so Paper wins If players choose the same weapon, neither win and the game is played again Program Specifications: The function eval_winner(p1, p2) must be used to determine the winner of a round p1 and p2 shall be one of the following values ', p', or 's' return a 0 if there is a tie, 1 if player 1 wins, and a 2 if player 2 wins If run as an independent program: The program will choose a weapon (Rock, Paper, Scissors), but its choice will not be displayed until later so the user doesn't see it. The program will announce the beginning of the round and ask the user for his/her weapon choice The two weapons will be compared to determine the winner (or a tie) and the results will be displayed by the program The next round will begin, and the game will continue until the user chooses to quit At the beginning of the game, the user should be prompted for his/her input. The valid choices for input are: o R orr (Rock) o P orp (Paper) o Sor s (Scissors) o Q or q (Quit)

Answer 1

The code is commented - explaining all the functions and operations used:

Edit: code is updated and so is the output

Code ( image ) :

1 use strict; 2 use warnings; 4 sub eval-winner #Defining our eval-winner function 6 #storing player! and player2's inputs 8 : my spl Ic s_[0]; #catching the first arguement passed in the function The 1c command changes the input to lowercase, so we can take care of an uppercase or lowercase input here 9 my Sp2 lc s [1]; catching the second arguement passed in the function The conditional statements that check for the winner : if (Spl eq Sp2) 12 #If both play er1 and player2 have the same input ie check this condition first because the condition's are shorter and it makes the progran faster return e; 17 elsif ((Spi eq-r-and Sp2 eq-s") or (S01 eq-s" and sp2 eq-p.) or (S01 eq-p" and Sp2 eq "r")) #Here we check all three cases for player1, if any of them are true-player1 wins return 1; 20 21 else #Since we have covered all the cases for a tie and player1 winning above, a sinple else statement will catch the rest of the conditions where player2 wins return 2 25 27 while () ·a loop with no parameter inside would be interpreted as true and become an infinite loop till we break it using "last" 29 print "Enter your choice: In 38 #Since we don't need global variables, we use my to declare local variables :

31 32 suser-weapon- <STDIN; #Here we take the users input chomp suser-weapon; #clean the user input 34 #lie, 11 quit the infinite loop here if the user types a q (Quit command) 35 if (Suser_weapon eq "q") 36 37 print "Turning off" 38 39 48 41 42 43 44 last; ast breaks out of the loop #Now we'll write the code that makes player2 (cpu) randomly choose a weapon my @weapons ("r","p", "s"); swe declare an array with the three options, to make it even more redundant and hence have a higher variation in the weapon the cpu chooses we can repeat the elements of the array eg. ("r,"p,s"r"P","r"p"s") and so on my $cpu-weapon : Sweapons[rand @weapons); #The cpu chooses a random weapon from the array #How does this work? "rand @weapons" r eturns a random index from the weapons array (i.e. from e, 1,2) and we pass that into the Sweapons array again to retreive that randon choice 47 my Sanswer eval_winner(Suser_weapon, scpu_weapon); #we call our function and store it in Sanswer to print the winner text on the screen print "It's a tiein 5e 51 52 elsif (Sanswer eq 1) 53 54 print "Player1 won! In" 56 57 58 59 6e print "player2 won! In"s

Output:

Enter your choice: Player1 won! Enter your choice Player1 won! Enter your choice It's a tie Enter your choice Turning offPress any key to continue . . .

Code (as plain text) :

use strict;
use warnings;

sub eval_winner #Defining our eval_winner function
{
#Storing player1 and player2's inputs
#The lc command changes the input to lowercase, so we can take care of an uppercase or lowercase input here
my $p1 = lc $_[0]; #catching the first arguement passed in the function
my $p2 = lc $_[1]; #catching the second arguement passed in the function

#The conditional statements that check for the winner
if ($p1 eq $p2) #If both player1 and player2 have the same input
{
#We check this condition first because the condition's are shorter and it makes the program faster
return 0;
}
elsif (($p1 eq "r" and $p2 eq "s") or ($p1 eq "s" and $p2 eq"p") or ($p1 eq "p" and $p2 eq "r")) #Here we check all three cases for player1, if any of them are true - player1 wins
{
return 1;
}
else #Since we have covered all the cases for a tie and player1 winning above, a simple else statement will catch the rest of the conditions where player2 wins
{
return 2;
}
}

while () #a loop with no parameter inside would be interpreted as true and become an infinite loop till we break it using "last"
{
print "Enter your choice: \n";
#Since we don't need global variables, we use my to declare local variables
my $user_weapon = <STDIN>; #Here we take the users input
chomp $user_weapon; #Clean the user input

#We'll quit the infinite loop here if the user types a q (Quit command)
if ($user_weapon eq "q")
{
print "Turning off";
last; #last breaks out of the loop
}

#Now we'll write the code that makes player2 (cpu) randomly choose a weapon
my @weapons = ("r","p","s"); #We declare an array with the three options, to make it even more redundant and hence have a higher variation in the weapon the cpu chooses
#we can repeat the elements of the array eg. ("r","p","s","r","p","s","r","p","s") and so on
my $cpu_weapon = $weapons[rand @weapons]; #The cpu chooses a random weapon from the array
#How does this work? "rand @weapons" returns a random index from the weapons array (i.e. from 0,1,2) and we pass that into the $weapons array again to retreive that random choice

my $answer = eval_winner($user_weapon,$cpu_weapon); #we call our function and store it in $answer to print the winner text on the screen
if ($answer eq 0)
{
print "It's a tie\n";
}
elsif ($answer eq 1)
{
print "Player1 won!\n";
}
else
{
print "Player2 won!\n";
}
}

1 use strict; 2 use warnings; 4 sub eval-winner #Defining our eval-winner function 6 #storing player! and player2's inputs 8 : my spl Ic s_[0]; #catching the first arguement passed in the function The 1c command changes the input to lowercase, so we can take care of an uppercase or lowercase input here 9 my Sp2 lc s [1]; catching the second arguement passed in the function The conditional statements that check for the winner : if (Spl eq Sp2) 12 #If both play er1 and player2 have the same input ie check this condition first because the condition's are shorter and it makes the progran faster return e; 17 elsif ((Spi eq-r-and Sp2 eq-s") or (S01 eq-s" and sp2 eq-p.) or (S01 eq-p" and Sp2 eq "r")) #Here we check all three cases for player1, if any of them are true-player1 wins return 1; 20 21 else #Since we have covered all the cases for a tie and player1 winning above, a sinple else statement will catch the rest of the conditions where player2 wins return 2 25 27 while () ·a loop with no parameter inside would be interpreted as true and become an infinite loop till we break it using "last" 29 print "Enter your choice: In 38 #Since we don't need global variables, we use my to declare local variables :

31 32 suser-weapon- <STDIN; #Here we take the users input chomp suser-weapon; #clean the user input 34 #lie, 11 quit the infinite loop here if the user types a q (Quit command) 35 if (Suser_weapon eq "q") 36 37 print "Turning off" 38 39 48 41 42 43 44 last; ast breaks out of the loop #Now we'll write the code that makes player2 (cpu) randomly choose a weapon my @weapons ("r","p", "s"); swe declare an array with the three options, to make it even more redundant and hence have a higher variation in the weapon the cpu chooses we can repeat the elements of the array eg. ("r,"p,s"r"P","r"p"s") and so on my $cpu-weapon : Sweapons[rand @weapons); #The cpu chooses a random weapon from the array #How does this work? "rand @weapons" r eturns a random index from the weapons array (i.e. from e, 1,2) and we pass that into the Sweapons array again to retreive that randon choice 47 my Sanswer eval_winner(Suser_weapon, scpu_weapon); #we call our function and store it in Sanswer to print the winner text on the screen print "It's a tiein 5e 51 52 elsif (Sanswer eq 1) 53 54 print "Player1 won! In" 56 57 58 59 6e print "player2 won! In"s

Sperl main.pl Enter your choice: q Player2 won! Enter your choice: p Turning off