We have discussed different approaches to swap two integers without the temporary variable. How to swap into a single line without using the library function?
1) Python: In Python, there is a simple and syntactically neat construct to swap variables, we just need to write “x, y = y, x”.
2) C/C++: Below is one generally provided classical solution:
// Swap using bitwise XOR (Wrong Solution in C/C++) x ^= y ^= x ^= y;
The above solution is wrong in C/C++ as it causes undefined behavior (the compiler is free to behave in any way). The reason is, modifying a variable more than once in an expression causes undefined behavior if there is no sequence point between the modifications.
However, we can use a comma to introduce sequence points. So the modified solution is
// Swap using bitwise XOR (Correct Solution in C/C++) // sequence point introduced using comma. (x ^= y), (y ^= x), (x ^= y);
3) Java: In Java, rules for subexpression evaluations are clearly defined. The left-hand operand is always evaluated before the right-hand operand. In Java, the expression “x ^= y ^= x ^= y;” doesn’t produce the correct result according to Java rules. It makes x = 0. However, we can use “x = x ^ y ^ (y = x);” Note the expressions are evaluated from left to right. If x = 5 and y = 10 initially, the expression is equivalent to “x = 5 ^ 10 ^ (y = 5);”. Note that we can’t use this in C/C++ as in C/C++, it is not defined whether the left operand or right operand is executed by any operator (See this for more details).
4) JavaScript: Using destructing assignment, we can simply achieve swapping using this one line.
[x,y]=[y,x]
C
// C program to swap two variables in single line#include <stdio.h>int main(){ int x = 5, y = 10; (x ^= y), (y ^= x), (x ^= y); printf("After Swapping values of x and y are %d %d", x, y); return 0;} |
C++
// C++ code to swap using XOR#include <bits/stdc++.h>using namespace std;int main(){ int x = 5, y = 10; // Code to swap 'x' and 'y' // to swap two numbers in one // line x = x ^ y, y = x ^ y, x = x ^ y; // printing the swapped variables cout << "After Swapping: x = " << x << ", y= " << y; return 0;} |
Java
// Java program to swap two variables in a single lineclass GFG { public static void main(String[] args) { int x = 5, y = 10; x = x ^ y ^ (y = x); System.out.println( "After Swapping values" +" of x and y are " + x + " " + y); }} |
Python3
# Python program to swap two variables in a single linex = 5y = 10x, y = y, xprint("After Swapping values of x and y are", x, y) |
C#
// C# program to swap two// variables in single lineusing System;class GFG { static public void Main() { int x = 5, y = 10; x = x ^ y ^ (y = x); Console.WriteLine("After Swapping values " + "of x and y are " + x + " " + y); }}// This code is contributed by aj_36 |
PHP
<?php// PHP program to swap two// variables in single line // Driver Code $x = 5; $y = 10; ($x ^= $y); ($y ^= $x); ($x ^= $y); echo "After Swapping values of x and y are " ,$x," ", $y;// This code is contributed by Vishal Tripathi?> |
Javascript
<script>// javascript program to swap two variables in single line let x = 5, y = 10; (x ^= y), (y ^= x), (x ^= y); document.write("After Swapping values of x and y are ", x + " ", y); // This code is contributed by Surbhi Tyagi</script> |
Output
After Swapping values of x and y are 10 5
Alternate Solutions:
- Using swap(): C++ library function
- b = (a + b) – (a = b);
- a += b – (b = a);
- a = a * b / (b = a)
- a = a ^ b ^ (b = a)
Time complexity : O(1)
Auxiliary Space : O(1)
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