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Command line versus GUI

The text in Figure 4 was produced using the Python (command line) interface. I don't get exactly the same behavior (with respect to prompts) when I use the Python GUI interface. Rather, what I get is shown in Figure 3 . (Note the missing ... prompt.)

The difference between the ... prompt and the>>>prompt is discussed in section 2.1.2. Interactive Mode of The Python Tutorial . (Note that the tutorial is also accessible in a different format from the Start/All Programs/Python 3.4 selection in Windows.)

Apparently the command-line interface creates the ... prompt when it thinks that the next line is a continuation line. The example given in the tutorial isshown in Figure 5 . (Don't be concerned if you don't understand the code in Figure 5 . I will explain similar code in a future module.)

Figure 5 . Example prompts from The Python Tutorial.
>>>the_world_is_flat = True>>>if the_world_is_flat: ... print("Be careful not to fall off!")... Be careful not to fall off!

Apparently for the case of Figure 4 , the system became confused by the comment and treated the line after the comment as a continuation line.

The IDLE GUI did not become confused in Figure 3 . I believe that it accomplishes line continuation by automatically indenting the next line and nocontinuation was required in either Figure 3 or Figure 4 .

Let's get technical

But not too technical. Computer programs are made up of statements.

Statements are composed of expressions.

(Later we will learn that large Python programs are made up of smaller programs called modules, which are made up of statements, which are composed ofexpressions.)

Statement ends at the end of the line

In Python, a statement normally ends at the end of the line that contains it (although there are exceptions to this rule) .

For the time being, suffice it to say that expressions are made up of

  • literal values
  • variables
  • operators
  • parentheses

Literal values and variables

Literal values are simply numbers that are included in an expression such as the 2 and the 5 shown in Figure 3 .

I will defer a discussion of variables until a future module, and will discuss operators and parentheses in the following paragraphs.

Operators

If you have ever used a hand calculator, you already know what operators are. The plus key on a hand calculator is an operator. The plus sign (+) in the expression shown in Figure 6 is also an operator.

Figure 6 . A Python addition operator.
>>>2+5

In programming jargon, operators are said to operate on operands ..

Operands

In Figure 6 , the 2 is the left operand and the 5 is the right operand of the + operator.

Unary and binary operators

Normally, operators are said to be either unary or binary .

A unary operator has only one operand while a binary operator has two operands.

Some can be either

Some operators, such as the minus sign (-), can be either unary or binary operators.

In its unary mode with a single operand, a minus sign is usually a sign changing operator, while in its binary mode with two operands, a minus sign is usually a subtraction operator.

Questions & Answers

what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Itse 1359 introduction to scripting languages: python. OpenStax CNX. Jan 22, 2016 Download for free at https://legacy.cnx.org/content/col11713/1.32
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