Readline(): Python Read File Line By Line

in this post, I’ll show you Reading a file using deadline() python method. The readline() is a built-in file method that helps read one complete line from the given file.

The built-in Python function readlines() returns all lines in a file as a list, with each line being an item in the list object.

We’ll be following steps to read a file in python:

• We’ll open a file using open() function
• The file object have readline() method to read content from text file.
• Finally, Close the file using close() function.

Python read text file line by line

The following code help to read all content from the test.txt file into a string.

Python file readlines() Example

The readline() function takes a line from a file and returns it as a string. It accepts a hint parameter that indicates the maximum number of bytes/lines to read. It will return an empty string if the file’s end is reached.

The syntax:
file.readlines(hint)

The hint is an optional parameter and is used to limit the amount of lines returned. The default value is -1, which means all lines will be returned.

Sample file

Let’s have a sample file test.txt. We’ll read this file using while loop:

Adam
James
Roy
Ron

Let’s write python script to read above file using while loop:

# Using readline()
file = open('test.txt', 'r')
count = 0

while True:
	count += 1

	# Get next line from file
	line = file.readline()

	# check end of file is reached
	if not line:
		break
	print("Line{}: {}".format(count, line.strip()))

file.close()

Output:

Line1 Adam
Line2 James
Line3 Roy
Line4 Ron

in the above code :

• We have opened test.txt file in read mode.
• Read line by line file till end of file is reached.
• Close the file.