Given a number N, check if it is positive, negative or zero without using conditional statements.
Examples:
Input : 30 Output : 30 is positive Input : -20 Output : -20 is negative Input: 0 Output: 0 is zero
The signed shift n>>31 converts every negative number into -1 and every other into 0.
When we do a -n>>31, if it is a positive number then it will return -1 as we are doing -n>>31 and the vice versa when we do for a negative number.
But when we do for 0 then n>>31 and -n>>31 both returns 0, so we get a formula:
1 + (n>>31) – (-n>>31)
..1) when n is negative :
1 +(-1)-0=0
..2) when n is positive:
1+0-(-1)=2
..3) when n is 0:
1+0-0=1
So we know it returns 0 when it is a negative number, it returns 1 when it is zero, returns 2 when it is a positive number.
So to not use if statements we store at 0th index “negative”, 1st index “zero” and at 2nd index “positive”, and print according to it.
// CPP program to find if a number is // positive, negative or zero using // bit wise operators. #include <iostream> using namespace std;
// function to return 1 if it is zero // returns 0 if it is negative // returns 2 if it is positive int index( int i)
{ return 1 + (i >> 31) - (-i >> 31);
} void check( int n)
{ // string array to store all kinds of number
string s[] = { "negative" , "zero" , "positive" };
// function call to check the sign of number
int val = index(n);
cout << n << " is " << s[val] << endl;
} // driver program to test the above function int main()
{ check(30);
check(-20);
check(0);
return 0;
} |
// Java program to find if a number is // positive, negative or zero using // bit wise operators. class GFG {
// function to return 1 if it is zero
// returns 0 if it is negative
// returns 2 if it is positive
static int index( int i)
{
return 1 + (i >> 31 ) - (-i >> 31 );
}
static void check( int n)
{
// string array to store all kinds
// of number
String s[] = { "negative" , "zero" ,
"positive" };
// function call to check the sign
// of number
int val = index(n);
System.out.println(n + " is " + s[val]);
}
// Driver code
public static void main(String[] args)
{
check( 30 );
check(- 20 );
check( 0 );
}
} // This code is contributed by Anant Agarwal. |
# Python 3 program to # find if a number is # positive, negative # or zero using # bit wise operators. # function to return 1 if it is zero # returns 0 if it is negative # returns 2 if it is positive def index(i):
return 1 + (i >> 31 ) - ( - i >> 31 )
def check(n):
# string array to store all kinds of number
s = "negative" , "zero" , "positive"
# function call to check the sign of number
val = index(n)
print (n, "is" ,s[val])
# driver program to # test the above function check( 30 )
check( - 20 )
check( 0 )
# This code is contributed by # Smitha Dinesh Semwal |
// C# program to find if a number is // positive, negative or zero using // bit wise operators. using System;
class GFG {
// function to return 1 if it is zero
// returns 0 if it is negative
// returns 2 if it is positive
static int index( int i)
{
return 1 + (i >> 31) - (-i >> 31);
}
static void check( int n)
{
// string array to store all kinds of number
String []s = { "negative" , "zero" , "positive" };
// function call to check the sign of number
int val = index(n);
Console.WriteLine(n + " is " + s[val]);
}
//Driver code
public static void Main()
{
check(30);
check(-20);
check(0);
}
} // This code is contributed by Anant Agarwal. |
<?php // PHP program to find if a number is // positive, negative or zero using // bit wise operators. // function to return 1 if it is zero // returns 0 if it is negative // returns 2 if it is positive function index( $i )
{ return 1 + ( $i >> 31) -
(- $i >> 31);
} function check( $n )
{ // string array to store
// all kinds of number
$s = array ( "negative" , "zero" , "positive" );
// function call to check
// the sign of number
$val = index( $n );
echo $n , " is " , $s [ $val ], "\n" ;
} // Driver Code
check(30);
check(-20);
check(0);
// This code is contributed by Ajit ?> |
// JavaScript program to find if a number is positive, negative or zero // function to return 1 if it is zero, 0 if it is negative, and 2 if it is positive function index(i) {
return 1 + (i >> 31) - (-i >> 31);
} function check(n) {
// string array to store all kinds of number
let s = [ "negative" , "zero" , "positive" ];
// function call to check the sign of number
let val = index(n);
console.log(`${n} is ${s[val]}`);
} // driver program to test the above function check(30); check(-20); check(0); |
Output:
30 is positive -20 is negative 0 is zero
Time Complexity : O(1)
Space Complexity : O(1)