Read Entire File into Buffer and Return as String in Python

When dealing with large files in Python, it is not efficient to read the entire file into memory at once. In such cases, we can read the file in chunks using a specified buffer size. This helps reduce memory consumption and allows for efficient processing of large files.

Following is the syntax of using the Buffer while reading a file -

with open('filename', 'r') as file:
   chunk = file.read(buffer_size)

Where,

• filename: The path of the file.
• 'r': Read mode
• buffer_size: Number of characters or bytes in binary mode to read at once.

Reading a File Using read() Function

We can read large files all at once using the read() function can be inefficient, so a better approach for reading the file is to split the data into small and manageable chunks.

Following is the example of reading an entire file into a buffer in the form of small chunks and returns the data as a string in Python -

buffer_size = 1
s
with open(r"D:\Tutorialspoint\Articles\file1.txt", "r") as file:
    while True:
        chunk = file.read(buffer_size)
        if not chunk:
            break
        print(chunk)

Here is the output of the above program -

Log entry:
 Applicati
on started

Reading a Binary Format File

Binary files such as images, audio, video, or any non-text files must be opened in binary mode 'rb' for reading in Python.

When dealing with large files, reading them in small chunks prevents memory overload and enhances performance.

Below is an example that shows how to read a binary file into a buffer -

buffer_size = 10

with open(r"D:\Tutorialspoint\Articles\file1.txt", "r") as file:
    while True:
        chunk = file.read(buffer_size)
        if not chunk:
            break
        print(chunk)

Here is the output of the above program -

b'Log entry: Application started\r\n'

Using io.StringIO to Read a String as a File

Python's io.StringIO module allows us to treat a string as a file-like object.

This method is useful when we want to simulate file operations such as reading and writing on strings instead of actual files.

Following is the example of reading the io.stringIo module to read a string from a file into a buffer -

import io

def read_string_into_buffer(data_string):
   buffer = io.StringIO(data_string)
   file_contents = buffer.read()
   return file_contents

# Example usage
data_string = "This is a string containing data that we want to read into a buffer."
file_contents = read_string_into_buffer(data_string)
print(file_contents)

Here is the output of the above program -

This is a string containing data that we want to read into a buffer.