检查给定整数是奇数还是偶数的 Java 程序
能被 2 整除并产生 0 的余数的数称为偶数。所有以 0、2、4、6 和 8 结尾的数字都是偶数。另一方面，不能被 2 整除并产生 1 的余数的数称为奇数。所有以 1、3、5、7 和 9 结尾的数字都是奇数。一定要参考下面的插图，通过任何随机整数的普通插图来了解这里应该传达的基本信息，检查它是偶数还是奇数。
Input : 13
Output: ODD
Input : 24
Output: EVEN
方法:
有各种方法可以检查给定的数字是奇数还是偶数。其中一些方法如下:从强力方法开始，到最优方法结束。
- 使用暴力-天真的方法
- 使用按位运算符
- 使用按位“或”
- 使用按位“与”
- 使用按位异或
- 通过检查最低有效位
方法 1: 蛮力天真法
它是检查除以 2 后的余数。能被 2 整除的数是偶数，否则是奇数。
例
Java 语言(一种计算机语言，尤用于创建网站)
// Java Program to Check if Given Integer is Odd or Even
// Using Brute Forcew Approach
// Importing required classes
import java.io.*;
import java.util.Scanner;
// Main class
class GFG {
// Main Driver Method
public static void main(String[] args)
{
// Declaring and initializing integer variable
int num = 10;
// Checking if number is even or odd number
// via remainder
if (num % 2 == 0) {
// If remainder is zero then this number is even
System.out.println("Entered Number is Even");
}
else {
// If remainder is not zero then this number is
// odd
System.out.println("Entered Number is Odd");
}
}
}
Output
Entered Number is Even
现在让我们详细讨论优化方法，如下所示，并借助按位运算符
方法 2: 使用按位运算符
- 按位“或”
- 按位与或按位异或
2-A:使用按位或
偶数按 1 的按位“或”运算使该数的值增加 1，否则该值保持不变。
图示:按位“或”
Number = 12 1 1 0 0 - Representation of 12 in Binary Format
Bitwise OR 0 0 0 1 - Representation of 1 in Binary Format
1 1 0 1 - Representation of 13 in Binary Format
Result- Number was even so bitwise Or by 1 increment the value by 1
Number = 15 1 1 1 1 - Representation of 15 in Binary Format
Bitwise OR 0 0 0 1 - Representation of 1 in Binary Format
1 1 1 1 - Representation of 15 in Binary Format
Result- Number was odd so bitwise Or by 1 doesn't increment the value by 1
例
Java 语言(一种计算机语言，尤用于创建网站)
// Java Program to Check if Given Integer is Odd or Even
// Using Bitwise OR
// Importing required classes
import java.util.*;
// Main class
public class GFG {
// Main driver method
public static void main(String[] args)
{
// Declaring and initializing integer variable
// to be checked
int n = 100;
// Condition check
// if n|1 if greater than n then this number is even
if ((n | 1) > n) {
// Print statement
System.out.println("Number is Even");
}
else {
// Print statement
System.out.println("Number is Odd");
}
}
}
Output
Number is Even
2-B:使用位“与”
奇数与 1 的按位“与”运算将为 1，因为最后一位已经设置，否则将为 0。
图示:按位“与”
Number = 5 0 1 0 1 - Representation of 5 in Binary Format
Bitwise AND 0 0 0 1 - Representation of 1 in Binary Format
0 0 0 1 - Representation of 1 in Binary Format
Result- Number was odd so bitwise And by 1 is 1
Number = 8 1 0 0 0 - Representation of 8 in Binary Format
Bitwise AND 0 0 0 1 - Representation of 1 in Binary Format
0 0 0 0 - Representation of 0 in Binary Format
Result- Number was even so bitwise And by 1 is 0
例
Java 语言(一种计算机语言，尤用于创建网站)
// Java Program to Check if Given Integer is Odd or Even
// Using Bitwise AND
// Importing required classes
import java.util.*;
// Main class
public class GFG {
// Main driver method
public static void main(String[] args)
{
// Declare and initializing integer variable
int n = 91;
// Condition Check
// Bitwise AND of any odd number by 1 gives 1
if ((n & 1) == 1) {
// Print statement
System.out.println("Number is Odd");
}
else {
// Print statement
System.out.println("Number is Even");
}
}
}
Output
Number is Odd
2-C:使用按位异或
偶数按 1 的逐位异或运算将数字的值增加 1，否则如果值为奇数，则将数字的值减少 1。这是最理想的方法。
图示:按位异或
Number = 5 0 1 0 1 - Representation of 5 in Binary Format
Bitwise XOR 0 0 0 1 - Representation of 1 in Binary Format
0 1 0 0 - Representation of 4 in Binary Format
Result- Number was odd so bitwise And by 1 decrement the value
Number = 8 1 0 0 0 - Representation of 8 in Binary Format
Bitwise XOR 0 0 0 1 - Representation of 1 in Binary Format
1 0 0 1 - Representation of 9 in Binary Format
Result- Number was even so bitwise And by 1 increment the value
例
Java 语言(一种计算机语言，尤用于创建网站)
// Java Program to Check if Given Integer is Odd or Even
// Using Bitwise XOR
// Importing required classes
import java.util.*;
// Main class
public class GFG {
// Main driver method
public static void main(String[] args)
{
// Declare and initializing integer variable
int num = 99;
// Condition Check
// if number^1 increments by 1 then its even number,
// else odd
if ((num ^ 1) == num + 1) {
// Print statement
System.out.println("Number is Even");
}
else {
// Print statement
System.out.println("Number is Odd");
}
}
}
Output
Number is Odd
方法 3: 检查数字的最低有效位
偶数的最低有效位总是 0，奇数的最低有效位总是 1。
例
Java 语言(一种计算机语言，尤用于创建网站)
// Java Program to Check if Given Integer is Odd or Even
// by checking the LSB of the Number
// Importing required classes
import java.util.*;
// Main class
// TestEvenOddByCheckingLSB
public class GFG {
// Method 1
// To test number is even or odd
public static String testOddEvenByCheckingLSB(int a)
{
if (a != 0) {
if (Integer.toBinaryString(a).endsWith("0")) {
return "Even";
}
else {
return "Odd";
}
}
// Here we will land if
// it does not ends with 0
else {
return "Zero";
}
}
// Method 2
// Main driver method
public static void main(String[] args)
{
// Iterationg over using for loop
for (int i = 0; i <= 10; i++) {
// Calling the function and printing
// corresponding number is even or odd
System.out.println(
i + " : " + testOddEvenByCheckingLSB(i));
}
}
}
Output
0 : Zero
1 : Odd
2 : Even
3 : Odd
4 : Even
5 : Odd
6 : Even
7 : Odd
8 : Even
9 : Odd
10 : Even
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