File Management in Python: Detailed Explanation

-

 

File Management in Python: Detailed Explanation

File management in Python allows us to create, open, read, write, rename, delete, and manipulate files and directories.

1. Opening Files

To open a file in Python, use the open() function.

Syntax:

file = open("filename", mode, encoding)
  • filename: Name or path of the file.
  • mode: Specifies the file operation mode.
  • encoding: Specifies the encoding format (e.g., UTF-8).

File Modes:

Mode Description
'r' Read mode (default). Opens file for reading only.
'w' Write mode. Creates a new file or overwrites the file.
'a' Append mode. Adds data to the end of the file.
'x' Create mode. Creates a new file; raises an error if the file already exists.
'b' Binary mode (e.g., 'rb', 'wb'). Used for binary files.
't' Text mode (default). Opens file in text mode.

Example: Opening a File

file = open("example.txt", "w")  # Open file in write mode
file.write("Hello, World!")      # Write to the file
file.close()                     # Close the file

2. File Attributes

When a file is opened, you can check its attributes:

  • file.name: Returns the file name.
  • file.mode: Returns the mode in which the file was opened.
  • file.closed: Returns True if the file is closed.

Example:

file = open("example.txt", "r")
print("File Name:", file.name)
print("Mode:", file.mode)
print("Is File Closed?", file.closed)
file.close()
print("Is File Closed?", file.closed)

Output:

File Name: example.txt
Mode: r
Is File Closed? False
Is File Closed? True

3. Reading and Writing Files

3.1 read() Method

Reads the file content.

Example:

file = open("example.txt", "r")
content = file.read()  # Reads entire file
print(content)
file.close()

3.2 readline() and readlines()

  • readline(): Reads one line at a time.
  • readlines(): Reads all lines into a list.

Example:

file = open("example.txt", "r")
line = file.readline()  # Reads first line
print("First Line:", line)

all_lines = file.readlines()  # Reads all lines
print("All Lines:", all_lines)
file.close()

3.3 write() Method

Writes data to the file. If the file doesn't exist, it will create one.

Example:

file = open("example.txt", "w")
file.write("Hello, Python!\n")
file.write("This is a new line.\n")
file.close()

3.4 writelines()

Writes a list of strings to the file.

Example:

file = open("example.txt", "w")
lines = ["Line 1\n", "Line 2\n", "Line 3\n"]
file.writelines(lines)
file.close()

4. tell() and seek() Methods

4.1 tell() Method

The tell() method returns the current position of the file pointer.

Example:

file = open("example.txt", "r")
print("Pointer Position:", file.tell())  # At the start

content = file.read(5)
print("Pointer Position after reading 5 characters:", file.tell())

file.close()

4.2 seek() Method

The seek() method changes the file pointer's position.

Syntax:

file.seek(offset, whence)
  • offset: Number of bytes to move.
  • whence:
    • 0: Start of file (default).
    • 1: Current position.
    • 2: End of file.

Example:

file = open("example.txt", "r")
file.seek(7)  # Move pointer to the 7th byte
content = file.read(5)
print("Read from position 7:", content)

file.close()

5. Closing Files

Always close a file after performing operations using file.close() or with statement.

Using with Statement:

The with statement automatically closes the file after use.

Example:

with open("example.txt", "r") as file:
    content = file.read()
    print(content)
# File is closed here automatically

6. Renaming and Deleting Files

Use the os module for file operations like renaming and deleting.

Renaming Files

Syntax:

import os
os.rename("old_name.txt", "new_name.txt")

Deleting Files

Syntax:

import os
os.remove("file_to_delete.txt")

Example:

import os

# Rename file
os.rename("example.txt", "new_example.txt")

# Delete file
os.remove("new_example.txt")

7. Directories in Python

Python's os module allows us to work with directories (folders).

Creating a Directory

import os
os.mkdir("new_folder")  # Creates a new folder

Deleting a Directory

import os
os.rmdir("new_folder")  # Removes an empty folder

Getting the Current Working Directory

import os
print("Current Directory:", os.getcwd())

Listing Files and Folders

import os
print("Files and Folders:", os.listdir("."))

8. Summary Table

Operation Method/Function Description
Open a file open() Opens a file in the specified mode.
Read file content read(), readline(), readlines() Reads file content.
Write to a file write(), writelines() Writes data to a file.
Close a file close() Closes the file after operations.
Move pointer seek(offset, whence) Moves file pointer to a specified location.
Check pointer position tell() Returns the current file pointer position.
Rename a file os.rename() Renames a file.
Delete a file os.remove() Deletes a file.
Create a directory os.mkdir() Creates a new directory.
Delete a directory os.rmdir() Deletes an empty directory.
List directory content os.listdir() Lists files and folders in a directory.

Example: Combining File Operations

import os

# Step 1: Create a new file and write to it
with open("sample.txt", "w") as file:
    file.write("Hello, this is a test file.\n")
    file.write("Python file management is easy.\n")

# Step 2: Read the file content
with open("sample.txt", "r") as file:
    print("File Content:")
    print(file.read())

# Step 3: Rename the file
os.rename("sample.txt", "test_file.txt")

# Step 4: Delete the file
os.remove("test_file.txt")

print("File operations completed successfully!")

Let me know if you need further clarification or examples! 😊

Comments

Post a Comment

Popular posts from this blog

Keyword , Identifier, Indentation, Comments & Documentation

-
Keyword : In Python, a  keyword  is a special word that has a specific meaning and purpose in the language. These words are reserved, which means you can’t use them for anything other than their intended purpose. For example, you can’t use a keyword as a variable name. Here are a few examples of Python keywords and what they do: if : Used to make a decision. For example,  if x > 0: . for : Used to create a loop. For example,  for i in range(10): . def : Used to define a function. For example,  def my_function(): . True  and  False : Represent boolean values.  I dentifier : In Python, an  identifier  is simply a name you give to things like variables, functions, classes, or modules. It’s like a label that helps you refer to these elements in your code. Here are some key points about identifiers: Must start with a letter or an underscore (_) : For example,  name ,  _value . Cannot start with a number : For example,  1name...
Read more

DSA Lab 8 program

-
 Program for implementing multiple stack. # include < stdio.h > # include < stdlib.h > struct stack {     int maxstack;     int * stack;     int top; }; int isEmpty ( struct stack * ptr ) {     if ( ptr -> top == - 1 ) {         return 1 ;     } else {         return 0 ;     } } int isFull ( struct stack * ptr ) {     if ( ptr -> top == ptr -> maxstack - 1 ) {         return 1 ;     } else {         return 0 ;     } } int peek ( struct stack * ptr ) {     return ptr -> stack [ ptr -> top ]; } int pop ( struct stack * ptr ) {     if ( isEmpty (ptr) ) {         printf ( " Stack Underflow! Cannot pop from the stack \n " ) ;         return - 1 ;     } else {         in...
Read more

DSA Lab 7 Program

-
 Program for implementing Stack using array # include < stdio.h > int maxstack = 10 ; int stack [ 10 ]; int top = - 1 ; int empty (){     if (top == - 1 ){         return 1 ;     }     else {         return 0 ;     } } int full (){     if (top == maxstack){         return 1 ;     }     else {         return 0 ;     } } int peek (){     return stack [top]; } int pop (){     int data;     if ( ! empty () ){         data = stack [top];         top -= 1 ;         printf ( " The data has been Deleted. Your data is %d \n " , data) ;         return data;     }     else {         printf ( " The data Can't be Deleted. Becouse stack is empty \n " ) ;   ...
Read more