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Escape sequences

Escape sequences are special sequences of characters used to represent other characters that

  • cannot be entered directly into a string, or
  • would cause a problem if entered directly into a string.

The newline character

An example of a character that cannot be entered directly into a string is the newline character. Except when using triple quoted strings, you cannot enter the newline character directly into astring.

Why? Because when you press the Enter key in an attempt to enter a newline, that simply terminates your input for that line. It doesn't enter thenewline character into the string.

The interactive code fragment in Figure 4 illustrates the use of an escape sequence to enter the newline character into a string. Note the \n between my first and last names.

Figure 4 . Using the newline character.
>>>print("Dick\nBaldwin") DickBaldwin>>>

The built-in print function

The Python interpreter has a number of functions built into it that are always available. They are listed in The Python Standard Library -- 2. Built-in Functions in alphabetical order. One of those functions is the print function.

The code in Figure 4 calls the print function to display my name on two output lines.

Historical note:

Up until version 3, Python had a print statement that did not require parentheses. In version 3, the print statement has been replaced with a print() function, with keyword arguments to replace most of the special syntax of the old print statement.

When the print function is used interactively, it is a request to have its argument (the expression in parentheses) printed on the next line. In Figure 4 , it is a request to have my name printed on the next line.

Including the newline character

In Figure 4 , I entered the newline escape sequence between my first and last names when I constructed the string. Then, when the string was printed, thecursor advanced to a new line following my first name and printed my last name on the new line. That is what escape sequences are all about.

The print function renders according to meaning

Note that the print function rendered the newline character according to its meaning.

By this, I mean that the print function did not print something that represented the newline character (\n) as we saw in Figure 3 . Instead, it actually did what a newline character is supposed to do -- go to the beginningof the next line.

The quote character

Escaping the quote character

Suppose that you are constructing a string that is surrounded by double quotes, and you want to use a pair of double quotes inside the string. If youwere to simply enter the double quote when you construct the string, that quote would terminate the string.

The interactive code fragment in Figure 5 shows how to escape the double quote character -- precede it with a backslash character.

Figure 5 . Escaping the quote character.
>>>print("Richard \"Dick\" Baldwin" ) Richard "Dick" Baldwin>>>

What I mean by this is that if you want to include a double quote inside a string that is surrounded by double quotes, you must enter the double quoteinside the string as shown in Figure 5 .

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
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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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