在C ++中不使用getline（）读取文本文件

Question

From what I learned, in order to analyze a text file, the go-to method is to analyze it line by line, which is easy and efficient.

However, when we're dealing with a huge file that has all the text in one line, the getline() function definitely would not be efficient at all. I'm wondering if there's any other efficient method to analyze this huge file?

The only thing I have in mind is to store this huge line into a string variable, and then cut it to singles words. But this still does not sound efficient at all.

Please help. Thank you!

Answer 1

You can use std::istream::get(char *, std::streamsize) to read large chunks of the file into a suitably-large buffer, and then process the file piecemeal, in large chunks.

Alternatively, there can be operating system-specific ways that can be used too. On Linux, a read-only mmap() of a file could be used to plow through it, with a minimum of fuss.

Answer 2

getline is basically just a shortcut for handling line-breaks - or other characters! So if your file has some delimiters (semicolon for example), you can use

std::getline(fileStream, stringToSave, ';');

As for performance - you just gotta try what works in your case.