Python 3 - File readline() Method


The method readline()reads one entire line from the file. A trailing newline character is kept in the string. If the size argument is present and non-negative, it is a maximum byte count including the trailing newline and an incomplete line may be returned.

An empty string is returned only when EOF is encountered immediately.


Following is the syntax for readline() method −

fileObject.readline( size );


size − This is the number of bytes to be read from the file.

Return Value

This method returns the line read from the file.


The following example shows the usage of readline() method.

Assuming that 'foo.txt' file contains following text:
This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line


# Open a file
fo = open("foo.txt", "r+")
print ("Name of the file: ",

line = fo.readline()
print ("Read Line: %s" % (line))

line = fo.readline(5)
print ("Read Line: %s" % (line))

# Close opened file


When we run the above program, it produces the following result −

Name of the file:  foo.txt
Read Line: This is 1st line

Read Line: This