使用位运算符
检查一个数字是正、负还是零
原文:https://www . geesforgeks . org/check-number-正数-负数-零-使用位运算符/
给定一个数字 N，在不使用条件语句的情况下检查它是正的、负的还是零。 示例:
Input : 30
Output : 30 is positive
Input : -20
Output : -20 is negative
Input: 0
Output: 0 is zero
有符号移位 n>>31 将每一个负数转换为-1，每隔一个负数转换为 0。 当我们做一个-n > > 31 时，如果它是一个正数，那么它会像我们做的那样返回-1-n>>31，反之亦然。 但是当我们对 0 做运算时，那么 n > > 31 和-n > > 31 都返回 0，所以我们得到一个公式:
1+(n > > 31)–(-n > > 31)
..1) 当 n 为负时 : 1 +(-1)-0=0 ..2) 当 n 为正时: 1+0-(-1)=2 ..3) 当 n 为 0 时: 1+0-0=1 所以我们知道它为负数时返回 0，为零时返回 1，为正数时返回 2。 所以为了不使用 if 语句，我们存储在第 0 个索引“负”，第 1 个索引“零”和第 2 个索引“正”，并根据它打印。
卡片打印处理机（Card Print Processor 的缩写）
// 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 语言(一种计算机语言，尤用于创建网站)
// 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
# 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
// 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.
服务器端编程语言（Professional Hypertext Preprocessor 的缩写）
<?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
?>
java 描述语言
<script>
// JavaScript 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
let s = [ "negative", "zero", "positive" ];
// function call to check the sign of number
let val = index(n);
document.write(n + " is " + s[val] + "<br>");
}
// driver program to test the above function
check(30);
check(-20);
check(0);
// This code is contributed by Surbhi Tyagi
</script>
输出:
30 is positive
-20 is negative
0 is zero
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