Handling multiple resources in Python

Introduction

Sometimes, you need to work with more than one file or resource at the same time. Handling multiple resources safely helps avoid mistakes and keeps your program clean.

When you want to read from one file and write to another at the same time.

When you need to open several files to compare their contents.

When you want to manage multiple network connections or database connections safely.

When you want to make sure all resources close properly even if an error happens.

Syntax

Python

with open('file1.txt') as file1, open('file2.txt') as file2:
    # work with file1 and file2 here

You can open multiple resources in one with statement separated by commas.

All resources will be closed automatically when the block ends.

Examples

This reads text from input.txt and writes it in uppercase to output.txt.

Python

with open('input.txt') as infile, open('output.txt', 'w') as outfile:
    data = infile.read()
    outfile.write(data.upper())

This opens two files and reads all lines from both.

Python

with open('file1.txt') as f1, open('file2.txt') as f2:
    lines1 = f1.readlines()
    lines2 = f2.readlines()

Sample Program

This program first creates two files with numbers. Then it opens both files at the same time, reads the numbers, and prints their sums.

Python

with open('numbers1.txt', 'w') as f1, open('numbers2.txt', 'w') as f2:
    f1.write('1\n2\n3\n')
    f2.write('4\n5\n6\n')

with open('numbers1.txt') as file1, open('numbers2.txt') as file2:
    nums1 = [int(line.strip()) for line in file1]
    nums2 = [int(line.strip()) for line in file2]

print('Sum of numbers1:', sum(nums1))
print('Sum of numbers2:', sum(nums2))

Important Notes

Using with for multiple resources keeps your code clean and safe.

If one resource fails to open, none will stay open accidentally.

You can use this pattern for files, network connections, or any resource that supports context management.

Summary

Use a single with statement to handle multiple resources together.

This ensures all resources close properly even if errors happen.

It makes your code easier to read and safer.