Chapter 6: Problem 13

What does it mean when the readline method returns an empty string?

Short Answer

Expert verified

Answer: The readline method returning an empty string signifies that the end of the file has been reached. When used in a loop, it allows the loop to be terminated when there are no more lines to read, preventing errors or infinite loops.

Step by step solution

Understanding the readline method

The readline method is commonly used to read a single line of text from a file. When using the readline method in a loop, it reads through a file line-by-line, until it reaches the end of the file.

Significance of an empty string

An empty string is a string with no characters in it, represented by '' or "". In the context of the readline method, it's important to know that when readline reaches the end of the file, it doesn't raise an error or exception; instead, it returns an empty string. This is the signal that there are no more lines to read from the file.

Application in a loop

When using readline method in a loop to read through a file, an empty string indicates that the end of the file has been reached, and thus the loop should be terminated. This can be done using a while loop and a conditional statement to check for an empty string. The loop will stop when it reaches the end of the file, preventing errors or infinite loops.

Example

Let's use a simple example to demonstrate this concept. Consider the following code: ``` with open('file.txt', 'r') as file: line = file.readline() while line != '': # Process the line print(line.strip()) line = file.readline() ``` In this example, the code reads the contents of "file.txt" line-by-line and prints each line (with stripped whitespace) in the terminal. The loop continues reading lines until it encounters an empty string, at which point it stops, signaling that the entire file has been read.

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What does it mean when the readline method returns an empty string?

Short Answer

Step by step solution

Understanding the readline method

Significance of an empty string

Application in a loop

Example

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