如何在不使用临时变量的情况下交换两个数字？

2021年4月13日10:20:12 发表评论 1,206 次浏览

本文概述

C++
C
Java
Python 3
C#
PHP
C++
C
Java
Python3
C#
PHP
C++
C
Java
Python3
C#
PHP
C++
C
Java
Python3
PHP
C++
C
Java
Python3
C#
PHP
C++

给定x和y这两个变量, 不使用第三个变量就交换两个变量。

方法1(使用算术运算符)

这个想法是获得两个给定数字之一的和。然后可以使用总和与总和相减来交换数字。

C++

//C++ Program to swap two numbers  without
//using temporary variable
#include <bits/stdc++.h>
using namespace std;
 
int main()
{
     int x = 10, y = 5;
 
     //Code to swap 'x' and 'y'
     x = x + y; //x now becomes 15
     y = x - y; //y becomes 10
     x = x - y; //x becomes 5
     cout <<"After Swapping: x =" <<x <<", y=" <<y;
}
 
//This code is contributed by mohit kumar.

C

#include <stdio.h>
int main()
{
     int x = 10, y = 5;
 
     //Code to swap 'x' and 'y'
     x = x + y; //x now becomes 15
     y = x - y; //y becomes 10
     x = x - y; //x becomes 5
 
     printf ( "After Swapping: x = %d, y = %d" , x, y);
 
     return 0;
}

Java

//Java Program to swap two numbers  without
//using temporary variable
import java.*;
 
class Geeks {
 
     public static void main(String a[])
     {
         int x = 10 ;
         int y = 5 ;
         x = x + y;
         y = x - y;
         x = x - y;
         System.out.println( "After swaping:"
                            + " x = " + x + ", y = " + y);
     }
}
 
//This code is contributed by Sam007

Python 3

x = 10
y = 5
  
# Code to swap 'x' and 'y'
 
# x now becomes 15
x = x + y 
 
# y becomes 10
y = x - y
 
# x becomes 5
x = x - y 
print ( "After Swapping: x =" , x, " y =" , y);
 
# This code is contributed
# by Sumit Sudhakar

C#

//Program to swap two numbers  without
//using temporary variable
using System;
 
class GFG {
     public static void Main()
     {
         int x = 10;
         int y = 5;
 
         x = x + y;
         y = x - y;
         x = x - y;
         Console.WriteLine( "After swapping: x = "
                           + x + ", y = " + y);
     }
}
 
//This code is contributed by Sam007

PHP

<?php
//PHP Program to swap two
//numbers without using
//temporary variable
$x = 10; $y = 5;
 
//Code to swap 'x' and 'y'
$x = $x + $y ; //x now becomes 15
$y = $x - $y ; //y becomes 10
$x = $x - $y ; //x becomes 5
 
echo "After Swapping: x = " , $x , ", " , "y = " , $y ;
 
//This code is contributed by m_kit
?>

输出：

After Swapping: x = 5, y = 10

乘法和除法也可以用于交换。

C++

//C++ Program to swap two numbers
//without using temporary variable
#include <bits/stdc++.h>
using namespace std;
 
int main()
{ //NOTE - for this code to work in a generalised sense, y !- 0 to prevent zero division
     int x = 10, y = 5;
 
     //Code to swap 'x' and 'y'
     x = x * y; //x now becomes 15
     y = x /y; //y becomes 10
     x = x /y; //x becomes 5
     cout <<"After Swapping: x =" <<x <<", y=" <<y;
}
 
//This code is contributed by mohit kumar.

C

#include <stdio.h>
int main()
{
     int x = 10, y = 5;
 
     //Code to swap 'x' and 'y'
     x = x * y; //x now becomes 50
     y = x /y; //y becomes 10
     x = x /y; //x becomes 5
 
     printf ( "After Swapping: x = %d, y = %d" , x, y);
 
     return 0;
}

Java

//Java Program to swap two numbers
//without using temporary variable
import java.io.*;
 
class GFG {
     public static void main(String[] args)
     {
         int x = 10 ;
         int y = 5 ;
 
         //Code to swap 'x' and 'y'
         x = x * y; //x now becomes 50
         y = x /y; //y becomes 10
         x = x /y; //x becomes 5
 
         System.out.println( "After swaping:"
                            + " x = " + x + ", y = " + y);
     }
}
 
//This code is contributed by ajit

Python3

# Python3 program to
# swap two numbers
# without using
# temporary variable
x = 10
y = 5
 
# code to swap
# 'x' and 'y'
 
# x now becomes 50
x = x * y
 
# y becomes 10
y = x //y;
 
# x becomes 5
x = x //y;
 
print ( "After Swapping: x =" , x, " y =" , y);
 
# This code is contributed
# by @ajit

C#

//C# Program to swap two
//numbers without using
//temporary variable
using System;
 
class GFG {
     static public void Main()
     {
         int x = 10;
         int y = 5;
 
         //Code to swap 'x' and 'y'
         x = x * y; //x now becomes 50
         y = x /y; //y becomes 10
         x = x /y; //x becomes 5
 
         Console.WriteLine( "After swaping:"
                           + " x = " + x + ", y = " + y);
     }
}
 
//This code is contributed by ajit.

PHP

<?php
//Driver code
     $x = 10;
     $y = 5;
 
//Code to swap 'x' and 'y'
     $x = $x * $y ; //x now becomes 50
     $y = $x /$y ; //y becomes 10
     $x = $x /$y ; //x becomes 5
 
echo "After Swapping: x = " , $x , " " , "y = " , $y ;
 
//This code is contributed by m_kit
?>

输出：

After Swapping: x = 5, y = 10

方法2(使用按位XOR)

按位XOR运算符可用于交换两个变量。两个数字x和y的XOR返回一个数字, 其中x和y的位不同时, 所有位都为1。例如, 10(在Binary 1010中)和5(在Binary 0101中)的XOR为1111, 而7(0111)和5(0101)的XOR为(0010)。

C++

//C++ code to swap using XOR
#include <bits/stdc++.h>
 
using namespace std;
 
int main()
{
     int x = 10, y = 5;
     //Code to swap 'x' (1010) and 'y' (0101)
     x = x ^ y; //x now becomes 15 (1111)
     y = x ^ y; //y becomes 10 (1010)
     x = x ^ y; //x becomes 5 (0101)
     cout <<"After Swapping: x =" <<x <<", y=" <<y;
     return 0;
}
 
//This code is contributed by mohit kumar.

C

//C code to swap using XOR
#include <stdio.h>
int main()
{
     int x = 10, y = 5;
 
     //Code to swap 'x' (1010) and 'y' (0101)
     x = x ^ y; //x now becomes 15 (1111)
     y = x ^ y; //y becomes 10 (1010)
     x = x ^ y; //x becomes 5 (0101)
 
     printf ( "After Swapping: x = %d, y = %d" , x, y);
 
     return 0;
}

Java

//Java code to swap using XOR
import java.*;
 
public class GFG {
 
     public static void main(String a[])
     {
         int x = 10 ;
         int y = 5 ;
 
         //Code to swap 'x' (1010) and 'y' (0101)
         x = x ^ y; //x now becomes 15 (1111)
         y = x ^ y; //y becomes 10 (1010)
         x = x ^ y; //x becomes 5 (0101)
 
         System.out.println( "After swap: x = "
                            + x + ", y = " + y);
     }
}
 
//This code is contributed by Sam007.

Python3

# Python 3 code to swap using XOR
 
x = 10
y = 5
 
# Code to swap 'x' and 'y'
x = x ^ y; # x now becomes 15 (1111)
y = x ^ y; # y becomes 10 (1010)
x = x ^ y; # x becomes 5 (0101)
 
print ( "After Swapping: x = " , x, " y =" , y)
 
# This code is contributed by
# Sumit Sudhakar

C#

//C# program to swap using XOR
using System;
 
class GFG {
     public static void Main()
     {
         int x = 10;
         int y = 5;
 
         //Code to swap 'x' (1010)
         //and 'y' (0101)
 
         //x now becomes 15 (1111)
         x = x ^ y;
 
         //y becomes 10 (1010)
         y = x ^ y;
 
         //x becomes 5 (0101)
         x = x ^ y;
 
         Console.WriteLine( "After swap: x = " + x + ", y = " + y);
     }
}
 
//This code is contributed by ajit

PHP

<?php
 
//Driver Code
$x = 10;
$y = 5;
 
//Code to swap 'x' (1010)
//and 'y' (0101)
 
//x now becomes 15 (1111)
$x = $x ^ $y ;
 
//y becomes 10 (1010)
$y = $x ^ $y ;
 
//x becomes 5 (0101)
$x = $x ^ $y ;
 
echo "After Swapping: x = " , $x , ", " , "y = " , $y ;
 
//This code is contributed by aj_36
?>

输出：

After Swapping: x = 5, y = 10

上述方法的问题

如果其中一个数字为0, 则乘积和除法将不起作用, 因为乘积将变为0, 而与另一个数字无关。

两种算术解决方案都可能导致算术溢出。如果x和y太大, 则加法和乘法可能超出整数范围。

当我们使用指向变量的指针并进行函数交换时, 当两个指针都指向同一个变量时, 上述所有方法都会失败。让我们看看如果两种情况都指向同一个变量, 将会发生什么情况。

//基于位异或的方法

x = x ^ x; // x变为0

x = x ^ x; // x保持为0

//基于算术的方法

x = x + x; // x变成2x

x = x – x; // x变为0

x = x – x; // x保持为0

让我们看下面的程序。

C++

#include <bits/stdc++.h>
using namespace std;
void swap( int * xp, int * yp)
{
     *xp = *xp ^ *yp;
     *yp = *xp ^ *yp;
     *xp = *xp ^ *yp;
}
 
//Driver code
int main()
{
     int x = 10;
     swap(&x, &x);
     cout<<"After swap(&x, &x): x = " <<x;
     return 0;
}
 
//This code is contributed by rathbhupendra

C

#include <stdio.h>
void swap( int * xp, int * yp)
{
     *xp = *xp ^ *yp;
     *yp = *xp ^ *yp;
     *xp = *xp ^ *yp;
}
 
int main()
{
     int x = 10;
     swap(&x, &x);
     printf ( "After swap(&x, &x): x = %d" , x);
     return 0;
}

Java

class GFG
{
     static void swap( int [] xp, int [] yp)
     {
         xp[ 0 ] = xp[ 0 ] ^ yp[ 0 ];
         yp[ 0 ] = xp[ 0 ] ^ yp[ 0 ];
         xp[ 0 ] = xp[ 0 ] ^ yp[ 0 ];
     }
     
     //Driver code
     public static void main(String[] args)
     {
         int [] x = { 10 };
         swap(x, x);
         System.out.println( "After swap(&x, &x): x = " + x[ 0 ]);
     }
}
 
//This code is contributed by Rajput-Ji

Python3

def swap(xp, yp):
 
     xp[ 0 ] = xp[ 0 ] ^ yp[ 0 ]
     yp[ 0 ] = xp[ 0 ] ^ yp[ 0 ]
     xp[ 0 ] = xp[ 0 ] ^ yp[ 0 ]
 
# Driver code
x = [ 10 ]
swap(x, x)
print ( "After swap(&x, &x): x = " , x[ 0 ])
 
# This code is contributed by SHUBHAMSINGH10

PHP

<?php
function swap(& $xp , & $yp )
{
     $xp = $xp ^ $yp ;
     $yp = $xp ^ $yp ;
     $xp = $xp ^ $yp ;
}
 
//Driver Code
$x = 10;
swap( $x , $x );
print ( "After swap(&x, &x): x = " . $x );
 
//This code is contributed
//by chandan_jnu
?>

输出：

After swap(&x, &x): x = 0

在许多标准算法中可能需要将变量本身交换。例如看

这个

实施

快速排序

我们可以在其中交换变量。通过在交换之前设置条件可以避免上述问题。

C++

#include <bits/stdc++.h>
using namespace std;
void swap( int * xp, int * yp)
{
     
     //Check if the two addresses are same
     if (xp == yp)
         return ;
     *xp = *xp + *yp;
     *yp = *xp - *yp;
     *xp = *xp - *yp;
}
 
//Driver Code
int main()
{
     int x = 10;
     swap(&x, &x);
     cout <<"After swap(&x, &x): x = " <<x;
     return 0;
}
 
//This code is contributed by rathbhupendra

C

#include <stdio.h>
void swap( int * xp, int * yp)
{
     if (xp == yp) //Check if the two addresses are same
         return ;
     *xp = *xp + *yp;
     *yp = *xp - *yp;
     *xp = *xp - *yp;
}
int main()
{
     int x = 10;
     swap(&x, &x);
     printf ( "After swap(&x, &x): x = %d" , x);
     return 0;
}

Java

//Java program of above approach
class GFG {
 
     static void swap( int xp, int yp)
     {
         if (xp == yp) //Check if the two addresses are same
             return ;
         xp = xp + yp;
         yp = xp - yp;
         xp = xp - yp;
     }
 
     //Driver code
     public static void main(String[] args)
     {
         int x = 10 ;
         swap(x, x);
         System.out.println( "After swap(&x, &x): x = " + x);
     }
}
 
//This code is Contributed by Code_Mech.

Python3

# Python3 program of above approach
def swap(xp, yp):
     
     # Check if the two addresses are same
     if (xp[ 0 ] = = yp[ 0 ]):
         return
     xp[ 0 ] = xp[ 0 ] + yp[ 0 ]
     yp[ 0 ] = xp[ 0 ] - yp[ 0 ]
     xp[ 0 ] = xp[ 0 ] - yp[ 0 ]
     
# Driver Code
x = [ 10 ]
swap(x, x)
print ( "After swap(&x, &x): x = " , x[ 0 ])
 
# This code is contributed by SHUBHAMSINGH10

C#

//C# program of above approach
using System;
class GFG {
 
     static void swap( int xp, int yp)
     {
         if (xp == yp) //Check if the two addresses are same
             return ;
         xp = xp + yp;
         yp = xp - yp;
         xp = xp - yp;
     }
 
     //Driver code
     public static void Main()
     {
         int x = 10;
         swap(x, x);
         Console.WriteLine( "After swap(&x, &x): x = " + x);
     }
}
 
//This code is Contributed by Code_Mech.

PHP

<?php
function swap( $xp , $yp )
{
     //Check if the two addresses
     //are same
     if ( $xp == $yp )
         return ;
     $xp = $xp + $yp ;
     $yp = $xp - $yp ;
     $xp = $xp - $yp ;
}
 
//Driver Code
$x = 10;
swap( $x , $x );
echo ( "After swap(&x, &x): x = " . $x );
return 0;
 
//This code is contributed
//by Code_Mech.

输出：

After swap(&x, &x): x = 10

方法3(按位运算符和算术运算符的混合)

这个想法与在

方法1

但是使用按位加减法进行交换。

下面是上述方法的实现。

C++

//C++ program to swap two numbers.
//Including header file.
#include<bits/stdc++.h>
using namespace std;
 
//Function to swap the numbers.
void swap( int &a, int &b)
{
     //same as a = a + b
     a = (a & b) + (a | b);
 
     //same as b = a - b
     b = a ^ b;
 
     //same as a = a - b
     a = a + (~b) + 1;
}
 
//Driver Code
int main()
{
     int a = 5, b = 10;
 
     //Function Call
     swap(a, b);
 
     cout <<"After swapping: a = " <<a <<
                                ", b = " <<b;
     
     return 0;
}
 
//This code is contributed by yashbeersingh42

输出：

After swapping: a = 10, b = 5

如果发现任何不正确的地方, 或者想分享有关上述主题的更多信息, 请发表评论。

本文概述

C++

C

Java

Python 3

C#

PHP

C++

C

Java

Python3

C#

PHP

C++

C

Java

Python3

C#

PHP

C++

C

Java

Python3

PHP

C++

C

Java

Python3

C#

PHP

C++

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