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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

what is variations in raman spectra for nanomaterials
Jyoti Reply
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
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
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
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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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