fgets() and fopen() with "w"

[vippstar]

What happends if I try to read from a stream which has been opened
with "w" mode, either with fgets or some other function?

 

[Walter Roberson]

What happends if I try to read from a stream which has been opened
with "w" mode, either with fgets or some other function?

fgets, C89:

If a read error occurs during the operation, the array contents
are indeterminate and a null pointer is returned.

Some of the other functions return EOF instead of a null pointer,
or return an unusual count -- depends on the exact function.

 

[vippstar]

fgets, C89:

If a read error occurs during the operation, the array contents
are indeterminate and a null pointer is returned.

Some of the other functions return EOF instead of a null pointer,
or return an unusual count -- depends on the exact function.

So what happends is a read error and not undefined behavior.
Thanks for the quick response.