Skip to main content

File IO in Python

 


Learning Sections          show

File IO in Python

File Input/Output (IO) operations allow you to read from and write to files. Python provides built-in functions and methods for file handling.

1. Opening a File

Use the open() function to open a file. It returns a file object and takes two parameters: the file name and the mode (e.g., read, write, append).


# Open a file in read mode
file = open('example.txt', 'r')

2. Reading from a File

After opening a file, you can read its contents using methods like read(), readline(), or readlines().


# Read entire content of the file
content = file.read()
print(content)

# Don't forget to close the file
file.close()

3. Writing to a File

Open a file in write ('w') or append ('a') mode to write data to it.


# Open a file in write mode
file = open('example.txt', 'w')

# Write a string to the file
file.write('Hello, World!')

# Close the file
file.close()

4. Using the with Statement

The with statement is used to wrap the execution of a block of code within methods defined by the context manager. It ensures that the file is properly closed after its suite finishes, even if an exception is raised.


# Using 'with' to open a file
with open('example.txt', 'r') as file:
    # Read the file's content
    content = file.read()
    print(content)

5. File Modes

Different modes can be used with the open() function:

  • 'r': Read (default mode)
  • 'w': Write (truncates the file)
  • 'a': Append
  • 'b': Binary mode
  • 't': Text mode (default mode)
  • '+': Read and write

# Example of opening a file in binary read mode
file = open('example.txt', 'rb')
# Example of opening a file in binary write mode
file = open('example.txt', 'wb')
Labels:

Popular posts from this blog

Generators in Python

  Learning Sections          show Generators in Python Generators are a special type of iterator in Python that allow you to iterate over a sequence of items without storing them all in memory at once. They are useful for generating large sequences of data on-the-fly, or for processing data in a memory-efficient manner. Creating Generators In Python, generators are created using generator functions or generator expressions: # Generator function def my_generator ( n ): for i in range ( n ): yield i # Generator expression my_generator = ( i for i in range ( 10 )) A generator function uses the yield keyword to yield values one at a time, while a generator expression creates an anonymous generator. Iterating Over Generators You can iterate over the values produced by a generator using a for loop: for value in my_generator ( 5 ): print ( value ) This w...
Read more

Inheritance in Python

  Learning Sections          show Inheritance in Python Inheritance is a fundamental concept in object-oriented programming (OOP) that allows a class to inherit attributes and methods from another class. The class that inherits is called the child class or subclass, and the class being inherited from is called the parent class or superclass. Basic Inheritance In Python, a child class inherits from a parent class by specifying the parent class in parentheses after the child class name. Example: class Animal : def __init__ ( self , name ): self . name = name def speak ( self ): raise NotImplementedError ( "Subclass must implement this method" ) class Dog ( Animal ): def speak ( self ): return "Woof!" class Cat ( Animal ): def speak ( self ): return "Meow!" # Create instances of Dog and Cat dog = Dog ( "Buddy" ) cat = Cat ( "Whiskers" ...
Read more

Walrus Operator in Python

  Learning Sections          show Walrus Operator in Python The walrus operator ( := ) is a new assignment operator introduced in Python 3.8. It allows you to assign values to variables as part of an expression, making certain constructs more concise. Basic Usage The basic syntax for the walrus operator is: variable_name := expression Here, variable_name is assigned the value of expression , and the result of the expression is also returned. Example: Simplifying Code Consider the following example where we find and print the length of a list if it's greater than 3: # Without walrus operator my_list = [ 1 , 2 , 3 , 4 ] if len ( my_list ) > 3 : length = len ( my_list ) print ( length ) # With walrus operator my_list = [ 1 , 2 , 3 , 4 ] if ( length := len ( my_list )) > 3 : print ( length ) In the second example, the walrus operator assigns the result of len(my...
Read more