Question

In python explain why would we want to read a file line by line instead of all at once?

Answer 1

Answer.

Step 1

In python readline() method returns one line from the file in the form of a string. We can also use the parameter as n which specifies the maximum number of bytes we can use. It will be efficient when reading a large file of fetching all data at once, it fetches line by line. This method returns the next line of the file which contains a newline character in the end. Also, if we reached the end of the file, it will return an empty string.

Step 2

Syntax: file.readline()

Example of readline() using while loop

# Python program to  demonstrate readline()

L = ["Made\n", "Easy\n", "Publications\n"]

# Writing to a file

file1 = open('myfile.txt', 'w')

file1.writelines((L))

file1.close()

  

# Using readline()

file1 = open('myfile.txt', 'r')

count = 0

#using while loop

while True:

  count += 1

  

  # Get next line from file

  line = file1.readline()

  

  # if line is empty

  # end of file is reached

  if not line:

  break

  print("Line{}: {}".format(count, line.strip()))

file1.close()

INPUT/OUTPUT:

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