Python File Handling - Complete Guide with Examples

1. File Handling Kya Hai?

File Handling ka matlab hai program ke madhyam se files ko create, read, write, update, aur manage karna. Python me file handling bahut aasan hai, jisme hum built-in functions aur methods ka use karke text ya binary files ko efficiently manipulate kar sakte hain.

2. Python me File Open Karna

Sabse pehla step hota hai file ko open karna using open() function. Is function me hum file ka naam aur mode specify karte hain:

file_object = open("filename.txt", mode)

Yahan mode specify karta hai ki file ko hum kaise use karna chahte hain, jaise:

• "r" - Read mode (default). File ko padhne ke liye kholta hai. Agar file nahi milegi to error aayega.
• "w" - Write mode. File ke content ko overwrite karta hai ya nayi file banata hai agar file nahi hai.
• "a" - Append mode. File ke end me naya data add karta hai, file nahi to banata hai.
• "x" - Create mode. Nayi file create karta hai, agar file exist karti hai to error dega.
• "b" - Binary mode, jaise images, audio files ke liye (r, w, a ke sath combine karte hain).
• "t" - Text mode (default).

3. File Reading

File ko read karne ke kai tareeke hain:

a) Puri File Read Karna

with open("example.txt", "r") as file:
content = file.read()
print(content)

b) Line by Line Read Karna

with open("example.txt", "r") as file:
for line in file:
print(line.strip())

c) readline() method

with open("example.txt", "r") as file:
line1 = file.readline()
line2 = file.readline()
print(line1.strip())
print(line2.strip())

4. File Writing

File me text ya data likhne ke liye write mode ya append mode use karte hain.

a) Write Mode

Ye mode file ke purane content ko overwrite kar deta hai.

with open("output.txt", "w") as file:
file.write("Hello, Python File Handling!\n")
file.write("Writing to file mode 'w' example.\n")

b) Append Mode

Ye mode file ke end me naye content ko add karta hai bina purane content ko hataye.

with open("output.txt", "a") as file:
file.write("This line is appended.\n")

5. File Closing

Jab hum with statement ka use karte hain to file automatically close ho jati hai. Agar bina with ke open karte hain to hume manually file.close() call karna padta hai.

6. Common File Handling Errors

• FileNotFoundError - Jab file read mode me open karte hain aur wo file exist nahi karti.
• PermissionError - File operations ke liye proper permission nahi hone par.

In errors ko handle karne ke liye try-except blocks use karte hain:

try:
with open("non_existent.txt", "r") as f:
print(f.read())
except FileNotFoundError:
print("File nahi mili! Please check name or path.")

7. File Cursor & seek() & tell() Methods

File read/write ke dauran cursor hota hai jo current position batata hai:

with open("example.txt", "r") as f:
print(f.read(5)) # Pehle 5 characters read karo
position = f.tell()
print("Cursor position:", position)
f.seek(0) # Cursor ko beginning pe le jao
print(f.read(5))

8. Binary File Handling

Images, audio ya binary files ke liye b mode use hota hai:

with open("image.jpg", "rb") as file:
data = file.read()
print(type(data)) # 

9. File Rename and Delete

Python ka os module file manage karne ke liye use hota hai:

import os

Rename file
os.rename("oldname.txt", "newname.txt")

Delete file
os.remove("newname.txt")

10. Summary

Python file handling ke zariye hum apne program se files ko efficiently create, read, write, aur manage kar sakte hain. open() function sabse important hai jisme alag-alag modes ka use karke file operations hote hain. with statement safe file handling ke liye best tareeka hai, jisse file khud-b-khud close ho jati hai.

File handling programming me data store aur access karne ke liye bahut zaruri skill hai, aur practice se isme mastery hasil ki ja sakti hai.