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An expression using literals

On the other hand, the following expression describes the sum of two literal numeric values:

sum = 6 + 8

No matter when this expression is evaluated, it will always produce a sum of 14.

String literals

Literal values can also be used for strings. For example, the interactive code fragment in Figure 1 shows

  • My name entered three times, in three different ways, on the interactive command line.
  • The output from the interpreter for each entry.
Figure 1 . String literals.
>>>"Dick Baldwin" 'Dick Baldwin'>>>'Dick Baldwin' 'Dick Baldwin'>>>Dick Baldwin SyntaxError: invalid syntax>>>

The first two entries are valid string literals. As you can see, in the first two cases, the interpreter displays my name in the output.

Note that in the first two cases, my name is surrounded by either quotes (sometimes called double quotes) or apostrophes (sometimes called single quotes) .

A syntax error

However, the third entry is not a valid string literal, and the interactive interpreter produced a SyntaxError message. (Although not shown in Figure 1 , the IDLE GUI interface highlighted my last name with a red backgroundimmediately above the SyntaxError message.) In the third case, my name is not surrounded by either double quotes or single quotes, and that is what causedthe error.

A valid string literal

Referring to String and Bytes literals , the Python Language Reference states:

Both types of literals can be enclosed in matching single quotes (') or double quotes (").

This explains why the first two input lines in the interactive code fragment in Figure 1 were accepted and the third input line produced an error.

Proper syntax

In the first input line in Figure 1 , my name was surrounded by matching double quotes. In the second input line, my name was surrounded by matching single quotes.

Bad syntax

However, in the third input line, my name was not surrounded by quotes of either type and this produced a syntax error.

More examples

Figure 2 shows two more examples of valid string literals.

Figure 2 . Triple-quoted strings.
>>>"""Dick Baldwin""" 'Dick Baldwin'>>>"""Dick Baldwin"""'Dick\nBaldwin'>>>===================================>>>"""Dick Baldwin""" 'Dick Baldwin'>>>"""Dick ... Baldwin"""'Dick \nBaldwin'>>>

The top half of Figure 2 was produced by the IDLE GUI interface. The bottom half was independently produced by the Python command-line interface.I included both of them to show you the output format difference between the two interfaces. In both cases, I pressed the Enter key following the input that reads """Dick.

Triple-quoted strings

Referring again to String and Bytes literals, the earlier quotation from the Python Language Reference goes on to state:

They can also be enclosed in matching groups of three single or double quotes (these are generally referred to as triple-quoted strings ). The backslash (\) character is used to escape characters that otherwise have aspecial meaning, such as newline, backslash itself, or the quote character.

Further down that same page we find:

Questions & Answers

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
what is biological synthesis of nanoparticles
Sanket Reply
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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