What is the meaning of this loop:- for(j = 1; j <= 10; j = j-1)

Answer 1

Almost an infinite loop. The value of j is reduced by 1 at each iteration so it will always be less than 10.

Answer 2

The loop will decrement <j> until its value exceeds negative value limit of type, and wraps around to a big positive value.

P.S. You didn't specify type of variable <j>.