Getting a segfault and a memory leak in C programm

As Karsten has said, you should spot this pretty easily with the debugger. How you use it depends on your compiler system, but a quick Google for the name of your IDE and "debugger" should give you the info you need.

Put a breakpoint on the first line in the function, and run your code through the debugger. Then look at your code, and at your data and work out what should happen manually. Then single step each line checking that what you expected to happen is exactly what did. When it isn't, that's when you have a problem, and you can back-track (or run it again and look more closely) to find out why.

Sorry, but we can't do that for you - time for you to learn a new (and very, very useful) skill: debugging!

I'll give you a hint though: When does this loop exit?

while (ende > anfang)
{
    i = *a;
    *a = *e;
    *e = i;

    ++a;
    --e;
}