Python String

What is a Python String?

In Python, a string is an ordered collection of characters enclosed in single quotes (') or double quotes ("). Strings are immutable, which means that once defined, their contents cannot be changed directly. Strings enable text processing and manipulation in Python.

Syntax

To create a string, you can use:

• Single quotes: 'Hello'
• Double quotes: "Hello"
• Triple quotes: '''Hello''' or """Hello""" (for multiline strings)

Examples

• Single-line Strings:

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    str1 = 'Hello'
    str2 = "World"
    print(str1)  # Output: Hello
    print(str2)  # Output: World
  

• Multi-line Strings:

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    multiline_str = """This is a 
    multiline string."""
    print(multiline_str)

  Output:

    This is a 
    multiline string.

String Operations

• Concatenation: Strings can be concatenated using the + operator to form a new string. + operator.

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    str1 = "Hello"
    str2 = "World"
    result = str1 + " " + str2
    print(result)  # Output: Hello World
  

• Repetition: A string can be duplicated multiple times using the * operator.

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    str1 = "Hi! "
    print(str1 * 3)  # Output: Hi! Hi! Hi!
  

• Indexing: Access specific characters using their index. Indexing starts at 0.

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    str1 = "Python"
    print(str1[0])  # Output: P
    print(str1[-1])  # Output: n (last character)
  

• Slicing: You can retrieve specific portions of a string using slicing syntax.

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    str1 = "Hello, World"
    print(str1[0:5])  # Output: Hello
    print(str1[:5])   # Output: Hello
    print(str1[7:])   # Output: World
  

String Methods

Python provides many built-in methods for string manipulation:

• len(): Get the length of a string.

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    str1 = "Hello"
    print(len(str1))  # Output: 5
  

• lower() and upper(): Change the case of a string using built-in methods .

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    str1 = "Python"
    print(str1.lower())  # Output: python
    print(str1.upper())  # Output: PYTHON
  

• strip(): Remove leading and trailing whitespace.

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    str1 = "   Hello   "
    print(str1.strip())  # Output: Hello
  

• replace(): Replace a substring with another string.

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    str1 = "Hello, World"
    print(str1.replace("World", "Python"))  # Output: Hello, Python
  

• split(): Split a string into a list based on a delimiter (default is space).

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    str1 = "Python is fun"
    print(str1.split())  # Output: ['Python', 'is', 'fun']
  

• find(): Locate the initial position of a substring using this method.

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    tr1 = "Python programming"
    print(str1.find("pro"))  # Output: 7
  

• in Keyword: Check if a substring exists in a string.

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    str1 = "Python programming"
    print("Python" in str1)  # Output: True
    print("Java" in str1)    # Output: False
    

Formatted Strings

Python provides ways to create formatted strings:

• Using f-strings (Python 3.6+):

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    name = "Alice"
    age = 25
    print(f"My name is {name} and I am {age} years old.")
   

• Using format():

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    name = "Alice"
    age = 25
    print("My name is {} and I am {} years old.".format(name, age))
  

Conclusion

Strings in Python are versatile and come with many built-in methods for manipulation. They are widely used in applications such as text processing, data formatting, and more.