Opening a file in 'a+ 'mode

Question

If a file is opened using the following command:

FILE *f1=fopen(\"test.dat\",\"a+\");

The man page reads:

a+

Answer 1

You can never mix reading and writing operations on a FILE without calling fseek in between. It may work as you wish on some implementations, but a program that depends on this has undefined behavior. Thus the questions of having 2 positions is meaningless.