Python Strings


Python Strings are amongst the most popular types in Python. We can create them simply by enclosing characters in quotes. Python treats single quotes the same as double quotes. Creating strings is as simple as assigning a value to a variable.

For example −

var1 = 'Hello Learners!'
var2 = "Python Programming"

Accessing Values in Strings

Python does not support a character type; these are treated as strings of length one, thus also considered a substring.

To access substrings, use the square brackets for slicing along with the index or indices to obtain your substring.

For example −

#!/usr/bin/python

var1 = 'Hello Learners!'
var2 = "Python Programming"

print "var1[0]: ", var1[0]
print "var2[1:5]: ", var2[1:5]

Output:

var1[0]:  H
var2[1:5]:  ytho

Updating Python Strings

You can “update” an existing string by (re)assigning a variable to another string. The new value can be related to its previous value or to a completely different string altogether.

For example −

var1 = 'Hello Wo#!/usr/bin/python

rld!'
print "Updated String :- ", var1[:6] + 'Python'

Output:

Updated String :-  Hello Python

Escape Characters

Following table is a list of escape or non-printable characters that can be represented with backslash notation.

An escape character gets interpreted; in a single quoted as well as double quoted strings.

Backslash notationHexadecimal characterDescription
\a0x07Bell or alert
\b0x08Backspace
\cx Control-x
\C-x Control-x
\e0x1bEscape
\f0x0cFormfeed
\M-\C-x Meta-Control-x
\n0x0aNewline
\nnn Octal notation, where n is in the range 0.7
\r0x0dCarriage return
\s0x20Space
\t0x09Tab
\v0x0bVertical tab
\x Character x
\xnn Hexadecimal notation, where n is in the range 0.9, a.f, or A.F

String Special Operators

Assume string variable a holds ‘Hello’ and variable b holds ‘Python’, then −

OperatorDescriptionExample
+Concatenation – Adds values on either side of the operatora + b will give HelloPython
*Repetition – Creates new strings, concatenating multiple copies of the same stringa*2 will give -HelloHello
[]Slice – Gives the character from the given indexa[1] will give e
[ : ]Range Slice – Gives the characters from the given rangea[1:4] will give ell
inMembership – Returns true if a character exists in the given stringH in a will give 1
not inMembership – Returns true if a character does not exist in the given stringM not in a will give 1
r/RRaw String – Suppresses actual meaning of Escape characters. The syntax for raw strings is exactly the same as for normal strings with the exception of the raw string operator, the letter “r,” which precedes the quotation marks. The “r” can be lowercase (r) or uppercase (R) and must be placed immediately preceding the first quote mark.print r’\n’ prints \n and print R’\n’prints \n
%Format – Performs String formattingSee at next section

Python Strings Formatting Operator

One of Python’s coolest features is the string format operator %. This operator is unique to strings and makes up for the pack of having functions from C’s printf() family.

Example:

#!/usr/bin/python

print "My name is %s and weight is %d kg!" % ('Zara', 21)

Output:

My name is Zara and weight is 21 kg!


Here is the list of complete set of symbols which can be used along with % −

Format SymbolConversion
%ccharacter
%sstring conversion via str() prior to formatting
%isigned decimal integer
%dsigned decimal integer
%uunsigned decimal integer
%ooctal integer
%xhexadecimal integer (lowercase letters)
%Xhexadecimal integer (UPPERcase letters)
%eexponential notation (with lowercase ‘e’)
%Eexponential notation (with UPPERcase ‘E’)
%ffloating point real number
%gthe shorter of %f and %e
%Gthe shorter of %f and %E

Other supported symbols and functionality are listed in the following table −

SymbolFunctionality
*argument specifies width or precision
left justification
+display the sign
<sp>leave a blank space before a positive number
#add the octal leading zero ( ‘0’ ) or hexadecimal leading ‘0x’ or ‘0X’, depending on whether ‘x’ or ‘X’ were used.
0pad from left with zeros (instead of spaces)
%‘%%’ leaves you with a single literal ‘%’
(var)mapping variable (dictionary arguments)
m.n.m is the minimum total width and n is the number of digits to display after the decimal point (if appl.)

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