Using a recursive parameter problem

When test(2, 'A', 'B', 'C') is invoked, then:

n = 2
c1 = 'A'
c2 = 'B'
c3 = 'C'

As n == 2, then test(1, 'A', 'C', 'B') is invoked recursively. In the recursive function call:

n = 1;
c1 = 'A'
c2 = 'C'
c3 = 'B'

So, when print(c1, c3) is called, we get A->B printed to the console.

The stack then unwinds back to the original call of the test function and the line print(c1, c3) is executed. In this call, we have the original parameter values of c1 ='A', c2 = 'B', c3 = 'C' and so we get A->C printed to the console.

The essential point here is that every function call has its own stack frame and therefore its own copy of the parameters.