Question

Possible Duplicate:
Double comparison

int x=-1;
if(0<=x<=9)
        std::cout<< "Without Logical operator";
if (0<=x && x<=9)
    std::cout<< "With Logical operator";

I know about 2nd if It’s working fine.
What’s happening here in the 1st if condition . It goes inside 1st if besides x is -1
And why compiler is not giving error when using (0<=x<=9)

Answer 1

In C, boolean values are just plain integers. In boolean context, 0 is false, and all other values are true. In this case,

(0 <= x <= 9)   ==
((0 <= x) <= 9) == // the (0 <= x) evaluates to 0, which is false in boolean context
(0 <= 9)        ==
1 (true)