How to Insert Lines into a File in Python Without Disrupting Existing Content?

Inserting Lines into a File in Python

Incorporating new data into a file while seamlessly adjusting the existing content can be a valuable technique. Consider a situation where you have a text file containing a list of names:

Alfred
Bill
Donald

Your task is to insert the name "Charlie" at a specific line (e.g., line 3) without manually shifting the remaining names down.

This can be achieved using Python's file handling capabilities:

<code class="python">with open("path_to_file", "r") as f:
    contents = f.readlines()

contents.insert(2, "Charlie")  # Index 2 represents line 3

with open("path_to_file", "w") as f:
    contents = "".join(contents)
    f.write(contents)</code>

In this code:

• readlines() reads the entire file into a list of lines.
• insert() inserts "Charlie" at the specified index (line number starting from 0).
• "".join(contents) concatenates the list of lines back into a single string.
• write() writes the updated string back into the file.

This method efficiently inserts lines into a file without disrupting the existing content.

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