<< Chapter < Page Chapter >> Page >

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

where we get a research paper on Nano chemistry....?
Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
ya I also want to know the raman spectra
Bhagvanji
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
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
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!





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
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Itse 1359 introduction to scripting languages: python' conversation and receive update notifications?

Ask