prgs

hello i want to know how the Turbo cpp (yes, the dinosaur one) and g++ give different output: a=10 ++a + ++a = 24 (g++) & 23 (TC) a++ + a++ = 20 ++a - a++ = 0 (g++) & -1(TC) please explain pre and post increment and decrement in this prgs. also please tell how to obtain output of such prgs...