Working with Files

20 min In Progress

Learning Objectives

  • Open, read, and write text files
  • Use with statements for safe file handling
  • Process CSV data

Reading a File

Use open() with mode 'r' to read. The with statement ensures the file closes automatically.

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

Writing a File

Use mode 'w' to overwrite or 'a' to append.

with open("output.txt", "w") as f:
    f.write("Hello, file!\n")
    f.write("Second line\n")

Reading Line by Line

Iterate over a file object to process one line at a time.

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

Course Example: Wage Calculator

Read a CSV, process wages, and write results to a new file.

import csv

# Simulated in-memory processing
import io
input_csv = "name,hours\nAlice,8\nBob,10"

output_data = []
reader = csv.reader(io.StringIO(input_csv))
next(reader)  # skip header
for row in reader:
    row[1] = int(row[1]) * 15
    output_data.append(row)

print(output_data)

📝 Exercise: Write a Poem

Write a list of lines to a file called poem.txt, then read it back and print it.

code.py
Output

            

        

    


    

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