Overview of String in Python
Strings in Python
Introduction to Strings:
Strings are a fundamental data type in Python, crucial for manipulating textual
information. They play a pivotal role in various programming tasks, from simple
text manipulation to complex data processing.
Commonly used for text processing, data representation, user interaction, and
file handling.
Key properties of strings
Immutability, versatility, and flexibility are among the key features of strings.
Strings can include letters, numbers, symbols, spaces, and characters from
many languages. They can be enclosed in single (' '), double (" "), or triple (''' ''' or
""" """) quotes for greater text representation versatility.
String Basics:
Definition :-
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Strings are sequences of characters, enclosed in single (' '), double (" "), or triple
(''' ''' or """ """) quotes.
Example:
message = "Hello, World!"
String Operations:
Concatenation: Joining strings using the + operator.
str1 = "Hello"
str2 = " World"
result = str1 + str2
# "Hello World"
Repetition: Repeating a string using the * operator.
repeated_str = "abc" * 3
# "abcabcabc"
String Indexing and Slicing:
Strings are zero-indexed, meaning the first character is at index 0.
text = "Python"
first_char = text[0]
# "P"
Slicing allows extracting a portion of a string.
substring = text[1:4]
# "yth"
String Methods:
len() : Returns the length of the string.
lower() / upper() : Converts the string to lowercase / uppercase.
strip() : Removes leading and trailing whitespaces.
replace(old, new) : Replaces occurrences of 'old' with 'new'.
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find(substring) / index(substring) : Returns the index of the first occurrence of the
substring.
Additional Advanced Methods:
split(separator) : Splits a string into a list of substrings based on the specified
separator.
sentence = "This is a sample sentence."
words = sentence.split() # ['This', 'is', 'a', 'sampl
e', 'sentence.']
join(iterable) : Joins elements of an iterable (e.g., a list) into a string using the
specified string as a separator.
words = ['This', 'is', 'a', 'sentence']
sentence = ' '.join(words) # 'This is a sentence'
translate(mapping) : Applies a translation table to replace specified characters.
translation_table = str.maketrans('aeiou', '12345')
text = "Hello, World!"
modified_text = text.translate(translation_table) # H2l
l4, W4rld!
Common String Operations:
Checking for Substrings:
sentence = "Python is powerful."
is_python_present = "Python" in sentence
# True
Reversing Strings:
reversed_str = sentence[::-1]
# ".lufrewop si nohtyP"
Converting Strings to Lists:
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char_list = list(sentence)
# ['P', 'y', 't', 'h', 'o',
'n', ' ', 'i', 's', ' ', 'p', 'o', 'w', 'e', 'r', 'f',
'u', 'l', '.']
String Formatting:
f-strings: Introduced in Python 3.6, they provide a concise way to embed
expressions inside string literals.
name = "Alice"
greeting = f"Hello, {name}!"
# "Hello, Alice!"
format() method: An older method for string formatting.
age = 25
message = "My age is {}".format(age)
Escape Characters: Use backslashes () to escape special characters within a
string.
escaped_str = "This is a line break.\nNow a new line."
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