Difference between r+ and w+ in fopen()

c fopen
yaylitzis picture yaylitzis · Jan 14, 2014 · Viewed 147k times · Source

In fopen("myfile", "r+") what is the difference between the "r+" and "w+" open mode? I read this:

"r" Open a text file for reading.
"w" Open a text file for writing, truncating an an existing file to zero length, or creating the file if it does not exist.

"r+" Open a text file for update (that is, for both reading and writing).
"w+" Open a text file for update (reading and writing), first truncating the file to zero length if it exists or creating the file if it does not exist.

I mean the difference is that if I open the file with "w+", the file will be erased first?

Answer

Peter picture Peter · Jan 14, 2014

Both r+ and w+ can read and write to a file. However, r+ doesn't delete the content of the file and doesn't create a new file if such file doesn't exist, whereas w+ deletes the content of the file and creates it if it doesn't exist.

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