diff --git a/perl/wiki b/perl/wiki
index 8842878..6311901 100644
--- a/perl/wiki
+++ b/perl/wiki
@@ -493,3 +493,317 @@
     }
 
     
+-> while loop:
+
+    print "==========Loop in Perl===========\n";
+    $a = 10;
+    # while loop execution & continue statement.
+    while ( $a < 15 ){
+        printf "Value of a: $a\n";
+        $a = $a + 1;
+    } continue {
+        $a = $a + 1;
+    }
+
+    print "while-loop ended here\n";
+
+    Output:
+    ==========Loops in Perl=============
+    Value of a: 10
+    Value of a: 12
+    Value of a: 14
+    while-loop ended here
+
+
+-> do - while loop:
+
+    For ex:
+
+    #do...while loop execution
+    do{
+        printf "Value of a: $a\n";
+        $a = $a + 1;
+    }while( $a < 10 );
+    print "do while-loop ended here\n"
+
+    Output:
+    Value of a:
+    Value of a: 1
+    Value of a: 2
+    Value of a: 3
+    Value of a: 4
+    Value of a: 5
+    Value of a: 6
+    Value of a: 7
+    Value of a: 8
+    Value of a: 9
+    do while-loop ended here
+
+-> until loop:
+
+    For ex:
+
+    #until loop execution
+    #negated while loop...
+    until( $a > 17 ){
+        printf "Value of a: $a\n"
+        $a = $a + 1;
+    }
+    printf "until-loop ended here\n";
+
+    Output:
+    Value of a:
+    Value of a: 1
+    Value of a: 2
+    Value of a: 3
+    Value of a: 4
+    Value of a: 5
+    Value of a: 6
+    Value of a: 7
+    Value of a: 8
+    Value of a: 9
+    Value of a: 10
+    Value of a: 11
+    Value of a: 12
+    Value of a: 13
+    Value of a: 14
+    Value of a: 15
+    Value of a: 16
+    Value of a: 17
+    until-loop ended here
+
+    
+-> for loop:
+
+    # for loop execution
+    for( $a = 10 ; $a < 20 ; $a = $a + 3){
+        print "value of a: $a\n"
+    }
+    print "for-loop ended here\n"
+
+    Output:
+    value of a: 10
+    value of a: 13
+    value of a: 16
+    value of a: 19
+    for-loop ended here
+
+-> foreach loop:
+
+    # foreach loop execution
+    @list = (200, 300, 400, 500);
+    foreach $a (@list){
+        print "value of a: $a\n"
+    }
+    print "foreach-loop ended here\n"
+
+    Output:
+    value of a: 200
+    value of a: 300
+    value of a: 400
+    value of a: 500
+
+-> next & redo ( next without label ):
+
+    * next: It's like a goto statement in C/C++
+    * redo: It's like a continue statement in C/C++
+    * last: It's like a break statement in C/C++
+
+    For ex:
+    #next and redo statements in loops
+
+    print "next statement example without label\n";
+    $a = 13;
+    while( $a < 18 ){
+        $a = $a + 1;
+        if( $a == 15 ){
+            #skip the iteration
+            $a = $a + 1;
+
+            #redo;
+            next;
+            #last: this keyword is like break statement in C/C++
+        }
+        print "value of a: $a\n";
+        #$a = $a + 1;
+    }
+
+    Output:
+    next statement example without label
+    value of a: 14
+    value of a: 17
+    value of a: 18
+
+-> next with labels:
+
+    For ex:
+    print "\nnext statement example with label\n";
+    $a = 0;
+    OUTER: while( $a < 4 ){
+        $b = 0;
+        print "value of a : $a\n";
+        INNER: while ( $b < 4 ){
+            if( $a == 2 ){
+                $a = $a + 1;
+                #jump to outer loop
+                next OUTER;
+                #last OUTER; #in case of last it will throw out of all nested loop
+            }
+            $b = $b + 1;
+            print "Value of b : $b\n"
+        }
+
+        print "\n";
+        $a = $a + 1;
+    }
+
+    Output:
+    next statement example with label
+    value of a: 0
+    value of b: 1
+    value of b: 2
+    value of b: 3
+    value of b: 4
+    
+    value of a: 1
+    value of b: 1
+    value of b: 2
+    value of b: 3
+    value of b: 4
+
+    value of a: 2
+    value of a: 3
+    value of b: 1
+    value of b: 2 
+    value of b: 3
+    value of b: 4
+
+
+-> Function in perl:
+
+    For ex:
+
+    print "\n==========Subroutines in Perl=======\n\n";
+
+    print "==== Passing scalars and arrays & returning result ====\n";
+    sub printSum{
+        print "In Average's subroutine: \$n = $n\n";
+        print "In Average's subroutine: \$sum = $sum\n";
+        print "In Average's subroutine: \$average = $average\n";
+    }
+
+
+    sub Average{
+        #get total number of arguments passed.
+        $n = scaler(@_);
+
+        # If array is passed as an argument to subroutine
+        # use @_ or if scalar is passed as an argument use
+        # $_.
+
+        #Scope of variables:
+        #this will be available to Average's subroutines
+        local $sum = 0; # Any function called from Average
+                        # subroutine can access $sum variable
+
+        foreach $item (@_){
+            $sum += $item;
+        }
+        printSum();
+
+        ##private variable
+        my $average = $sum / $n;
+        return $average;
+    }
+
+    #Function call
+    @a = (40, 50, 60);
+
+    $b = 70;
+    $avg = Average(10, 20, 30, @a, $b);
+    print "Average for the given numbers: $avg\n";
+    print "\$sum = $sum\n";
+    print "\$n = $n\n";
+    print "\$average = $average\n";
+
+
+    Output:
+
+    ====Subroutines in Perl====
+
+    ==== Passing scalars and array & returning result ===
+    In Average's subroutine: $n = 7
+    In Average's subroutine: $sum = 280
+    In Average's subroutine: $average = 
+    Average for the given number : 40
+    $sum =
+    $n = 7
+    $avearge = 
+
+
+
+-> Passing hashes in subroutines:
+
+    For ex:
+
+    %cardG1CPUarch = ('csc01', 'mips', 'xcc360g', 'ppc', 'cef4c', 'ppc');
+
+    print "===== Passing hashes to subroutines ====\n";
+    #Function definition
+    sub  PrintHash{
+        my (%hash) = @_;
+
+        foreach my $key ( keys %hash ){
+            my $value = $hash{$key};
+            print "$key : $value\n";
+        }
+    }
+
+    #Function call with hash parameter
+    PrintHash(%cardG1CPUarch);
+
+    Output:
+
+    ====== Passing hashes to subroutines ======
+    cef4c: ppc
+    xcc360g: ppc
+    csc01: mips
+
+
+-> References in Perl:
+
+    For ex:
+    print "\n==== References in Perl =====\n\n";
+
+    $var = 10;
+    # Now $r has reference to $var scalar.
+    $r = \$var;
+    # Print value available at the location stored in $r.
+    print "Type of reference is :" . ref($r) . "\n";
+    print "Value of $var is: " , $$r, "\n";
+
+    @var = (1,2,3);
+    #Now $r has reference to @var array.
+    $r = \@var;
+    #Print values available at the location stored in $r.
+    print "Type of reference is :" . ref($r) . "\n";
+    print "Value of @var is :" . @$r, "\n";
+
+    %var = ('key1' => 10, 'key2' => 20);
+    # Now $r has reference to $var has.
+    $r = \%var;
+    # Print values available at the location stored in $r.
+    print "Type of reference is :" . ref($r) . "\n";
+    print "Value of %var is : " , $r, "\n";
+    print "Value of %var is : " , %$r{'key1'}, "\n";
+
+    Output:
+    ====== Refernce in Perl ======
+
+    Type of reference is : SCALAR
+    Value of 10 is : 10
+    Type of reference is : ARRAY
+    Value of 1 2 3 is : 123
+    Type of reference is : HASH
+    Value of %var is : key220key110
+    Value of %var is : key110
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