associativity of operators

Hello friends,

I am following Let us C, 6th edition, by Yashavant Kanetkar,

I have problem understanding the concept of associativity of operators,

I tried to find some good material on internet by searching in google but could not find much.

Kanetkar writes,

"Left to Right associativity means that the left operand must be unambiguous. Unambiguous in what sense? It must not be involved in evaluation of any other sub-expression. Similarly in case of Right to Left associativity the right operator must be unambiguous."

I could not understand what it means by "being unambiguous".

There is a expression,

In his solution book, he gives the solution.

Code:

` operator left Right Remark`

/ 10 5 or 5/2/1 Left operand is unambiguous,

Right is not

/ 10/5 or 5 2 or 2/1 Left operand is unambiguous,

Right is not

/ 10/5/2 or 2 1 Right operand is unambiguous,

Left is not

now in first row and right column why he writes only two operands that are possible: 5 or 5/2/1 why also not 5/2

In the second row in the remark column why he says that left operand is unambiguous when there are two operands that are possible i.e. 10/5 or 5.

Thanks a lot