How to determine if a number is positive or negative?

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I was asked in an interview, how to determine whether a number is positive or negative. The rules are that we should not use relational operators such as <, and >, built in java functions (like substring, indexOf, charAt, and startsWith), no regex, or API's.

I did some homework on this and the code is given below, but it only works for integer type. But they asked me to write a generic code that works for float, double, and long.

 // This might not be better way!!

 S.O.P ((( number >> 31 ) & 1) == 1 ? "- ve number " : "+ve number );

any ideas from your side?

numbers java
32 Answers

Two simple solutions. Works also for infinities and numbers -1 <= r <= 1 Will return "positive" for NaNs.

String positiveOrNegative(double number){
    return (((int)(number/0.0))>>31 == 0)? "positive" : "negative";
}

String positiveOrNegative(double number){
    return (number==0 || ((int)(number-1.0))>>31==0)? "positive" : "negative";
}
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