10.3 Files: Handling Text Files with Multiple Lines

Objective

This section focuses on writing pseudo-code to manage text files that contain one or more lines. We will cover operations such as opening, reading, and potentially writing to such files.

Pseudo-code: Reading a Text File Line by Line

The following pseudo-code outlines the steps involved in reading a text file line by line.

1. Open the file:

   Attempt to open the specified text file in read mode (e.g., 'r').

   If the file cannot be opened, display an error message and terminate the process.

2. Read lines iteratively:

   Create a loop that continues as long as there are more lines to read in the file.

   Inside the loop:

   • Read a single line from the file.
   • Store the read line in a variable.
   • Process the read line (e.g., print it, store it in a data structure, perform some analysis).
3. Close the file:

   After the loop has finished (all lines have been read), close the file to release system resources.

   If the file could not be opened initially, the close operation is skipped.

Pseudo-code: Writing to a Text File Line by Line

The following pseudo-code outlines the steps involved in writing data to a text file, line by line.

1. Open the file:

   Attempt to open the specified text file in write mode (e.g., 'w') or append mode (e.g., 'a').

   If the file cannot be opened, display an error message and terminate the process.

2. Iterate through the data:

   Assume you have a collection of data (e.g., a list or array) where each element represents a line to be written.

   Create a loop that iterates through each element in the data collection.

   • Write the current element to the file, followed by a newline character ('').
3. Close the file:

   After the loop has finished (all lines have been written), close the file to ensure the data is saved to the disk.

   If the file could not be opened initially, the close operation is skipped.

Example Scenario: Processing a Log File

Consider a scenario where you need to process a log file. The file contains multiple lines of log entries. You might want to read each line, extract specific information (e.g., timestamps, error messages), and perform some analysis.

Example Pseudo-code: Writing Lines to a New File

Here's a simple example of pseudo-code to write a few lines to a new text file.

Assume we have a list of strings called data.

1. Open a new file called output.txt in write mode.
2. For each string line in data:
   • Write line to the file.
   • Write a newline character ('') to the file.
3. Close the output.txt file.