问题
I do not understand the difference between the "ab" and "rb+" modes when using fopen() in C.
Why would I choose one instead of the other?
回答1:
With the mode specifiers above the file is open as a text file. In order to open a file as a binary file, a
"b"character has to be included in the mode string. This additional"b"character can either be appended at the end of the string (thus making the following compound modes:"rb","wb","ab","r+b","w+b","a+b") or be inserted between the letter and the"+"sign for the mixed modes ("rb+","wb+","ab+").
From fopen documentation which I advise you read before asking questions. It will give you a lot of information about possible parameters, return values, similar functions etc.
Also, from the same document :
"a"= append: Open file for output at the end of a file. Output operations always write data at the end of the file, expanding it. Repositioning operations (fseek,fsetpos,rewind) are ignored. The file is created if it does not exist.
"r+"= read/update: Open a file for update (both for input and output). The file must exist.
来源：https://stackoverflow.com/questions/43978465/what-is-the-difference-between-rb-and-ab-in-fopen