In Python, a string is an immutable sequence of Unicode characters. Each character has a unique numeric value as per the UNICODE standard. But, the sequence as a whole, doesn’t have any numeric value even if all the characters are digits. To differentiate the string from numbers and other identifiers, the sequence of characters is included within single, double or triple quotes in its literal representation. Hence, 1234 is a number (integer) but ‘1234’ is a string.
Creating Python Strings
As long as the same sequence of characters is enclosed, single or double or triple quotes don’t matter. Hence, following string representations are equivalent.
Example
>>>'Welcome To TutorialsPoint''Welcome To TutorialsPoint'>>>"Welcome To TutorialsPoint"'Welcome To TutorialsPoint'>>>'''Welcome To TutorialsPoint''''Welcome To TutorialsPoint'>>>"""Welcome To TutorialsPoint"""'Welcome To TutorialsPoint'
Looking at the above statements, it is clear that, internally Python stores strings as included in single quotes.
In older versions strings are stored internally as 8-bit ASCII, hence it is required to attach ‘u’ to make it Unicode. Since Python 3, all strings are represented in Unicode. Therefore, It is no longer necessary now to add ‘u’ after the string.
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 −
var1 ='Hello World!'
var2 ="Python Programming"print("var1[0]: ", var1[0])print("var2[1:5]: ", var2[1:5])
When the above code is executed, it produces the following result −
var1[0]: H var2[1:5]: ytho
Updating 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 World!'print("Updated String :- ", var1[:6]+'Python')
When the above code is executed, it produces the following result −
Updated String :- Hello Python
Visit our Python – Modify Strings tutorial to know more about updating/modifying strings.
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 notation | Hexadecimal character | Description |
|---|---|---|
| \a | 0x07 | Bell or alert |
| \b | 0x08 | Backspace |
| \cx | Control-x | |
| \C-x | Control-x | |
| \e | 0x1b | Escape |
| \f | 0x0c | Formfeed |
| \M-\C-x | Meta-Control-x | |
| \n | 0x0a | Newline |
| \nnn | Octal notation, where n is in the range 0.7 | |
| \r | 0x0d | Carriage return |
| \s | 0x20 | Space |
| \t | 0x09 | Tab |
| \v | 0x0b | Vertical 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 −
| Operator | Description | Example |
|---|---|---|
| + | Concatenation – Adds values on either side of the operator | a + b will 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 index | a[1] will give e |
| [ : ] | Range Slice – Gives the characters from the given range | a[1:4] will give ell |
| in | Membership – Returns true if a character exists in the given string | H in a will give 1 |
| not in | Membership – Returns true if a character does not exist in the given string | M not in a will give 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 “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 formatting | See at next section |
String 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. Following is a simple example −
print("My name is %s and weight is %d kg!"%('Zara',21))
When the above code is executed, it produces the following result −
My name is Zara and weight is 21 kg!
Here is the list of complete set of symbols which can be used along with % −
| Sr.No. | Format Symbol & Conversion |
|---|---|
| 1 | %ccharacter |
| 2 | %sstring conversion via str() prior to formatting |
| 3 | %isigned decimal integer |
| 4 | %dsigned decimal integer |
| 5 | %uunsigned decimal integer |
| 6 | %ooctal integer |
| 7 | %xhexadecimal integer (lowercase letters) |
| 8 | %Xhexadecimal integer (UPPERcase letters) |
| 9 | %eexponential notation (with lowercase ‘e’) |
| 10 | %Eexponential notation (with UPPERcase ‘E’) |
| 11 | %ffloating point real number |
| 12 | %gthe shorter of %f and %e |
| 13 | %Gthe shorter of %f and %E |
Other supported symbols and functionality are listed in the following table −
| Sr.No. | Symbol & Functionality |
|---|---|
| 1 | *argument specifies width or precision |
| 2 | –left justification |
| 3 | +display the sign |
| 4 | <sp>leave a blank space 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. |
| 6 | 0pad from left with zeros (instead of spaces) |
| 7 | %‘%%’ leaves you with a single literal ‘%’ |
| 8 | (var)mapping variable (dictionary arguments) |
| 9 | m.n.m is the minimum total width and n is the number of digits to display after the decimal point (if appl.) |
Visit our Python – String Formatting tutorial to learn about various ways to format strings.
Double Quotes in Python Strings
You want to embed some text in double quotes as a part of string, the string itself should be put in single quotes. To embed a single quoted text, string should be written in double quotes.
Example
var ='Welcome to "Python Tutorial" from TutorialsPoint'print("var:", var)
var ="Welcome to 'Python Tutorial' from TutorialsPoint"print("var:", var)
It will produce the following output −
var: Welcome to "Python Tutorial" from TutorialsPoint var: Welcome to 'Python Tutorial' from TutorialsPoint
Triple Quotes
To form a string with triple quotes, you may use triple single quotes, or triple double quotes − both versions are similar.
Example
var ='''Welcome to TutorialsPoint'''print("var:", var)
var ="""Welcome to TutorialsPoint"""print("var:", var)
It will produce the following output −
var: Welcome to TutorialsPoint var: Welcome to TutorialsPoint
Python Multiline Strings
Triple quoted string is useful to form a multi-line string.
Example
var ='''
Welcome To
Python Tutorial
from TutorialsPoint
'''print("var:", var)
It will produce the following output −
var: Welcome To Python Tutorial from TutorialsPoint
Arithmetic Operators with Strings
A string is a non-numeric data type. Obviously, we cannot use arithmetic operators with string operands. Python raises TypeError in such a case.
print("Hello"-"World")
On executing the above program it will generate the following error −
>>> "Hello"-"World" Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: unsupported operand type(s) for -: 'str' and 'str'
Getting Type of Python Strings
A string in Python is an object of str class. It can be verified with type() function.
Example
var ="Welcome To TutorialsPoint"print(type(var))
It will produce the following output −
<class 'str'>
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