Analysis of the problem that \ r \ n cannot be used to write phpfwrite txt files

The following describes the problem that \ r \ n cannot be used for line breaks when fwrite in php writes a txt file, if you want to write a txt file with fwrite, you can refer to the following problem: rn cannot be used for line feed.
I haven't found a solution after trying for a long time!
I suddenly thought that I had read a book before and used this stuff to solve it!
I want to help my friends who need help in preventing future forgetting!
View the code directly:

For more information about the problem that \ r \ n cannot be used for line breaks when writing php fwrite to a txt file, see The PHP Chinese website!