How To Add Letter To String Python

Python iii - Strings

Strings are among the nearly popular types in Python. We can create them simply past enclosing characters in quotes. Python treats single quotes the same equally double quotes. Creating strings is as simple as assigning a value to a variable. For example −

var1 = 'Hello World!' 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, employ the square brackets for slicing along with the index or indices to obtain your substring. For example −

#!/usr/bin/python3  var1 = 'Hello World!' var2 = "Python Programming"  print ("var1[0]: ", var1[0]) impress ("var2[1:5]: ", var2[1:5])

When the higher up lawmaking is executed, it produces the following result −

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

Updating Strings

You can "update" an existing string past (re)assigning a variable to some other string. The new value tin can be related to its previous value or to a completely different string birthday. For case −

#!/usr/bin/python3  var1 = 'Hello Earth!' print ("Updated String :- ", var1[:half-dozen] + 'Python')

When the above code is executed, it produces the following result −

Updated String :-  Hello Python

Escape Characters

Following tabular array is a list of escape or not-printable characters that tin can be represented with backslash annotation.

An escape character gets interpreted; in a unmarried quoted every bit well as double quoted strings.

Backslash note	Hexadecimal character	Description
\a	0x07	Bong or alarm
\b	0x08	Backspace
\cx		Control-10
\C-x		Command-10
\east	0x1b	Escape
\f	0x0c	Formfeed
\One thousand-\C-x		Meta-Command-x
\n	0x0a	Newline
\nnn		Octal annotation, where due north is in the range 0.7
\r	0x0d	Carriage render
\due south	0x20	Space
\t	0x09	Tab
\v	0x0b	Vertical tab
\x		Grapheme ten
\xnn		Hexadecimal notation, where n is in the range 0.ix, a.f, or A.F

String Special Operators

Presume string variable a holds 'Hello' and variable b holds 'Python', and then −

Operator	Description	Example
+	Concatenation - Adds values on either side of the operator	a + b volition give HelloPython
*	Repetition - Creates new strings, concatenating multiple copies of the same string	a*2 will give -HelloHello
[]	Slice - Gives the character from the given alphabetize	a[1] will give e
[ : ]	Range Slice - Gives the characters from the given range	a[1:4] volition give ell
in	Membership - Returns true if a graphic symbol exists in the given string	H in a volition give 1
not in	Membership - Returns true if a character does non exist in the given string	Chiliad not in a will requite 1
r/R	Raw 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 of the alphabet "r," which precedes the quotation marks. The "r" can be lowercase (r) or capital letter (R) and must be placed immediately preceding the first quote mark.	impress r'\due north' prints \northward and print R'\northward'prints \n
%	Format - Performs String formatting	See at next section

Cord Formatting Operator

One of Python's coolest features is the string format operator %. This operator is unique to strings and makes upwards for the pack of having functions from C's printf() family. Post-obit is a simple example −

#!/usr/bin/python3  print ("My proper noun is %due south and weight is %d kg!" % ('Zara', 21))

When the to a higher place code is executed, it produces the following result −

My proper name is Zara and weight is 21 kg!

Hither is the list of consummate set up of symbols which can exist used along with % −

Sr.No.	Format Symbol & Conversion
1	%c character
2	%s string conversion via str() prior to formatting
iii	%i signed decimal integer
4	%d signed decimal integer
5	%u unsigned decimal integer
6	%o octal integer
7	%x hexadecimal integer (lowercase letters)
8	%Ten hexadecimal integer (UPPERcase letters)
nine	%e exponential notation (with lowercase 'e')
x	%East exponential note (with Uppercase 'East')
eleven	%f floating point real number
12	%g the shorter of %f and %eastward
13	%One thousand the shorter of %f and %Due east

Other supported symbols and functionality are listed in the post-obit tabular array −

Sr.No.	Symbol & Functionality
1	* argument specifies width or precision
2	- left justification
iii	+ display the sign
iv	<sp> get out a blank infinite before a positive number
5	# add the octal leading zero ( '0' ) or hexadecimal leading '0x' or '0X', depending on whether 'x' or 'X' were used.
six	0 pad from left with zeros (instead of spaces)
vii	% '%%' leaves you with a single literal '%'
8	(var) mapping variable (dictionary arguments)
9	m.n. m is the minimum total width and north is the number of digits to display after the decimal point (if appl.)

Triple Quotes

Python's triple quotes comes to the rescue past allowing strings to span multiple lines, including verbatim NEWLINEs, TABs, and any other special characters.

The syntax for triple quotes consists of three consecutive single or double quotes.

#!/usr/bin/python3  para_str = """this is a long string that is made up of several lines and not-printable characters such as TAB ( \t ) and they will prove upwardly that manner when displayed. NEWLINEs inside the string, whether explicitly given like this within the brackets [ \n ], or merely a NEWLINE inside the variable assignment will also testify upwards. """ print (para_str)

When the above code is executed, it produces the following issue. Note how every unmarried special character has been converted to its printed grade, correct downwards to the last NEWLINE at the end of the cord between the "upward." and closing triple quotes. As well note that NEWLINEs occur either with an explicit carriage return at the end of a line or its escape code (\n) −

this is a long cord that is made up of several lines and not-printable characters such as TAB (    ) and they will show up that way when displayed. NEWLINEs within the string, whether explicitly given like this inside the brackets [  ], or just a NEWLINE within the variable consignment will also show up.

Raw strings do not care for the backslash as a special grapheme at all. Every character y'all put into a raw string stays the way yous wrote it −

#!/usr/bin/python3  impress ('C:\\nowhere')

When the above lawmaking is executed, information technology produces the following consequence −

C:\nowhere

Now allow's make employ of raw string. We would put expression in r'expression' as follows −

#!/usr/bin/python3  print (r'C:\\nowhere')

When the above code is executed, it produces the following result −

C:\\nowhere

Unicode String

In Python three, all strings are represented in Unicode.In Python ii are stored internally every bit viii-fleck ASCII, hence it is required to attach 'u' to make it Unicode. It is no longer necessary now.

Congenital-in String Methods

Python includes the following built-in methods to manipulate strings −

Sr.No.	Methods & Description
1	capitalize() Capitalizes commencement letter of string
2	centre(width, fillchar) Returns a cord padded with fillchar with the original cord centered to a full of width columns.
three	count(str, beg = 0,cease = len(cord)) Counts how many times str occurs in string or in a substring of string if starting index beg and ending index cease are given.
four	decode(encoding = 'UTF-8',errors = 'strict') Decodes the string using the codec registered for encoding. encoding defaults to the default string encoding.
5	encode(encoding = 'UTF-8',errors = 'strict') Returns encoded cord version of string; on error, default is to enhance a ValueError unless errors is given with 'ignore' or 'replace'.
half dozen	endswith(suffix, beg = 0, end = len(cord)) Determines if string or a substring of string (if starting alphabetize beg and ending index end are given) ends with suffix; returns true if so and imitation otherwise.
seven	expandtabs(tabsize = viii) Expands tabs in string to multiple spaces; defaults to 8 spaces per tab if tabsize not provided.
8	find(str, beg = 0 finish = len(cord)) Determine if str occurs in string or in a substring of string if starting index beg and ending alphabetize stop are given returns index if found and -1 otherwise.
9	index(str, beg = 0, end = len(cord)) Same as find(), but raises an exception if str not found.
10	isalnum() Returns true if string has at least 1 grapheme and all characters are alphanumeric and false otherwise.
11	isalpha() Returns true if string has at least ane character and all characters are alphabetic and false otherwise.
12	isdigit() Returns truthful if string contains only digits and false otherwise.
13	islower() Returns truthful if cord has at least 1 cased graphic symbol and all cased characters are in lowercase and false otherwise.
14	isnumeric() Returns truthful if a unicode string contains merely numeric characters and false otherwise.
15	isspace() Returns truthful if string contains just whitespace characters and false otherwise.
16	istitle() Returns truthful if string is properly "titlecased" and false otherwise.
17	isupper() Returns truthful if string has at least one cased character and all cased characters are in uppercase and false otherwise.
xviii	join(seq) Merges (concatenates) the string representations of elements in sequence seq into a string, with separator string.
19	len(cord) Returns the length of the string
twenty	ljust(width[, fillchar]) Returns a space-padded cord with the original string left-justified to a total of width columns.
21	lower() Converts all uppercase letters in string to lowercase.
22	lstrip() Removes all leading whitespace in cord.
23	maketrans() Returns a translation tabular array to be used in translate function.
24	max(str) Returns the max alphabetical character from the cord str.
25	min(str) Returns the min alphabetical character from the cord str.
26	replace(quondam, new [, max]) Replaces all occurrences of one-time in string with new or at most max occurrences if max given.
27	rfind(str, beg = 0,terminate = len(string)) Same as find(), just search backwards in cord.
28	rindex( str, beg = 0, terminate = len(cord)) Same every bit index(), but search backwards in string.
29	rjust(width,[, fillchar]) Returns a space-padded string with the original string right-justified to a full of width columns.
thirty	rstrip() Removes all trailing whitespace of string.
31	separate(str="", num=string.count(str)) Splits string co-ordinate to delimiter str (space if not provided) and returns list of substrings; split into at most num substrings if given.
32	splitlines( num=string.count('\north')) Splits cord at all (or num) NEWLINEs and returns a list of each line with NEWLINEs removed.
33	startswith(str, beg=0,cease=len(string)) Determines if string or a substring of string (if starting index beg and catastrophe index terminate are given) starts with substring str; returns true if so and false otherwise.
34	strip([chars]) Performs both lstrip() and rstrip() on string
35	swapcase() Inverts example for all letters in string.
36	title() Returns "titlecased" version of string, that is, all words brainstorm with uppercase and the rest are lowercase.
37	interpret(table, deletechars="") Translates string according to translation table str(256 chars), removing those in the del cord.
38	upper() Converts lowercase letters in string to uppercase.
39	zfill (width) Returns original string leftpadded with zeros to a full of width characters; intended for numbers, zfill() retains any sign given (less ane zero).
40	isdecimal() Returns true if a unicode string contains but decimal characters and false otherwise.