Perl Tutorial

Hello everyone. Welcome back to VLSI Academy. This is third lecture on

part programming language and today we will begin with something called

Lists in PURL. When we define a scalar variable such as this, it is nothing but a

list with one scalar variable. When we define an array like this, it has nothing

but a list with collection of different items. And we define a hash like this.

It is nothing but a list with different key value pairs. Hence in above

examples, all three lists are of scalar array and hash type. Hence an array is

a variable but all of PURL's data type. Scalar array and hash can provide a

list which is simply an ordered or unordered set of scalars. Moving on,

generally speaking lists are collection of scalars. This is a list of characters,

this is a list of integers, this is a list of strings. As you can see, you use

the parenthesis and comma operators to construct a list. Each value in the list is

called a list element. List elements are indexed and ordered. You can refer to

each element by its position. So from now on, we will refer to all the arrays as

lists only. As this is a common terminology in the PURL platform. Now as we know,

list is a collection of scalars. Hence it is also ordered and can be

referenced with the index values. This is how we declare the list and to access

its element, we just have to specify the index value in the list name and since

it is a scalar value, we just have to specify the prefix with the dollar. We can

also access list element from the last. The last element index will be minus one.

So when you run it in the command line, fourth element of the output will be

Uma and when the you run the second line in the command line, output should be

Suresh. Moving on to other features of list is list slicing. So you can assign

from one array a slice to the other array. So the PURL interpreter has no

problem with this statement because it copies the list stored in one three and

five location into a temporary location which is invisible to the user before

assigning it to the new names 0 1 and 2. So how do you do is first you will

declare this name list and after that you will assign it to new list new name

list. So name 1 3 5 will go to new name 0 1 2 and print new name of 1 will give

output and command line as Manju which is this variable here. That's all for today.

We will see more features of list in next video. Please share and subscribe to

the channel for more updates. Thank you.

Hello everyone, welcome to VLSI Academy. This is fifth lecture and today we will discuss

about conditional statements in Perl. Consider a case where employees are classified based

on their salary. If the salary is greater than 10,000, then it will be tagged as manager

and if it is lesser than 10,000, then you have to tag it as staff. So to write such a

code first, we will declare the variable salary, which based on which you have to classify.

And then if condition is written something like this, if the salary is greater than 10,000,

then print employee is manager. So here we have taken this example just to give you the

idea how the syntax looks like for if condition in Perl, which is very similar to how we write

in C. Now, else if condition is something like this, where else if salary is lesser than

10,000, then you have to print employee is staff. Here you just have to note else if condition

it is E L S I F not E L S E E I F. So E is missing here, which is very peculiar to

Perl. Now moving on Perl has a very peculiar feature which is different than other platform

and that is unless condition, which means that it will execute the statement if it evaluates

to false and it will not execute and it will exit out if the evaluation of the statement

is true. So let's say you have a variable 22. So for example, if you want to put unless

condition with this condition that variable lesser than 20 and if you put the condition

to print this statement, so it will evaluate this and 22 is lesser than 20, this is false.

So it will go inside it and it will print and if it is true, then it will not go inside

it. So strictly speaking, it is actually if along with not statement. So it will evaluate

to false and if it is false, then it will go inside. Let us move on to very commonly

use the switch statement, which is present in all platforms with almost similar functionality

everywhere. For using the switch statement in Perl, first you have to declare the switch

statement and this is the variable based on which we will choose between the different

cases which we have to consider. So let's say we have an array and we have a hash. Now

this is the switch statement syntax where you have to declare this variable inside the

parenthesis after the switch and with this parenthesis, we will start our switch statement.

So and first case is case 10 so case 10 if it matches the variable matches to this value

then it will print number 100. If the variable matches to a it will print string A. If

the variable matches to this list, it will print numbers discontinuously and if the

variable value matches to this array then it will print numbering no list. If the variable

value matches to hash, it will print entry in hash. If none of the matches, then it will

print else condition. So in C, you will have default here.

here it is else in the burl and this is the parenthesis close of this switch statement.

So since our value is 30 so it will go and it will check it is not 30 it does not fall

inside this list also but it will be array and array is this 1020 30 so it is present here

so it will go here and number in array list will be printed.

Let us now explore some of the commonly used control statements which comes very handy

while writing a program and helps the programmer to write a program easily and efficiently.

So here are some of them.

Next statement will escape the remainder of the loop and goes back to the beginning

of the loop.

While last statement will exit the loop and hand over the execution to the statement

after the loop.

Redo statement will restart the loop again with the previously tested condition.

Go to statement transfer the program controlled to a particular label or expression just

like C programming.

Let us all for this video we have provided you the basic idea and we will see their usage

in the real life examples later on.

In next video we will see the different loops and their examples in the purl.

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