I got a large text file, and I want to find different sentences (strings) in this file.

What would be an efficient way to go through the file and look for different sentences?

I can read every line, and create tens of 'if' to see if each line contains any sentence.

I can also create a switch-case loop that goes through each line.

However, it doesn't sound that efficient.

I'd love to hear your suggestions.

Thanks in advance.