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File Handling

Read from and write to files using Python's built-in file functions.

File Handling

Python can read and write files using the built-in open() function. Always use with statements to ensure files are properly closed.

Syntax

<pre><code># Writing to a file
with open("data.txt", "w") as f:
    f.write("Hello, World!\n")
    f.write("Second line\n")

# Reading from a file
with open("data.txt", "r") as f:
    content = f.read()    # Entire file as string
    print(content)

# Read line by line
with open("data.txt", "r") as f:
    for line in f:
        print(line.strip())

# Append to file
with open("data.txt", "a") as f:
    f.write("Appended line\n")

# File modes: r=read, w=write, a=append, rb/wb=binary
import os
if os.path.exists("data.txt"):
    os.remove("data.txt")
</code></pre>

Revision Notes

• with open() as f: auto-closes file
• Modes: r, w, a, rb, wb
• read() = whole file; readline() = one line; readlines() = list
• write() / writelines() to write
• os.path.exists() check before operations

Count Words in Text

Medium

Write a function count_words(text) that takes a multi-line string (simulating file content) and returns the total number of words across all lines.

Input:

"Hello world\nThis is Python\nGoodbye"

Output:

Show Hint

Split the text by whitespace (which handles newlines too) using text.split(), then count the resulting list length.

Solve this Challenge

Show Solution

def count_words(text):
    return len(text.split())

print(count_words("Hello world\nThis is Python\nGoodbye"))

Try / Except

File Handling

File Handling

Syntax

Revision Notes

File Handling Quiz

Count Words in Text