Question

computer. p=10, q= 15,R=20,S = 17, t=21,U= 6 z=++p+r+q++ + ++S+t++ + ++U+t++ + p+r++ + q+U+S++​

Answer 1

Answer:

The output of above programs and all such programs can be easily guessed by remembering following simple rules about postfix ++, prefix ++ and * (dereference) operators

1) Precedence of prefix ++ and * is same. Associativity of both is right to left.

2) Precedence of postfix ++ is higher than both * and prefix ++. Associativity of postfix ++ is left to right.

(Refer: Precedence Table)

The expression ++*p has two operators of same precedence, so compiler looks for associativity. Associativity of operators is right to left. Therefore the expression is treated as ++(*p). Therefore the output of first program is “arr[0] = 11, arr[1] = 20, *p = 11“.

The expression *p++ is treated as *(p++) as the precedence of postfix ++ is higher than *. Therefore the output of second program is “arr[0] = 10, arr[1] = 20, *p = 20 “.

The expression *++p has two operators of same precedence, so compiler looks for associativity. Associativity of operators is right to left. Therefore the expression is treated as *(++p). Therefore the output of third program is “arr[0] = 10, arr[1] = 20, *p = 20“.

Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above