File Handling

Python provides built-in functions to read from and write to text files.

Reading from a File

Function	Description
open("filename.txt", "r")	Opens a file in read mode.
file.read()	Reads the entire file as a single string.
file.readline()	Reads one line at a time.
file.readlines()	Reads all lines and stores them in a list.
with open("filename.txt", "r") as file:	Best practice for handling files (auto-closes file).
.strip()	Removes leading and trailing whitespace or newline characters from a string.

Example:

with open("students.txt", "r") as file:
    content = file.read()
print(content)  # Prints entire file as a string

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Writing to a File

Function	Description
open("filename.txt", "w")	Opens a file in write mode (erases existing content).
open("filename.txt", "a")	Opens a file in append mode (adds content without erasing).
file.write(text)	Writes a string to the file.
file.writelines(list_of_strings)	Writes multiple lines from a list.

Example:

with open("students.txt", "w") as file:
    file.write("Alice\nBob\nCharlie\n")  # Writes names to file

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Closing a File

Function	Description
file.close()	Closes the file (not needed if using with open(...)).