We have discussed different approaches to swap two integers without the temporary variable. How to swap in a single line without using library function?
Python: In Python, there is a simple and syntactically neat construct to swap variables, we just need to write “x, y = y, x”.
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 behaviour (compiler is free to behave in any way). The reason is, modifying a variable more than once in an expression causes undefined behaviour if there is no sequence point between the modifications.
However, we can use 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);
Java: In Java, rules for subexpression evaluations are clearly defined. The left hand operand is always evaluated before right hand operand (See this for more details). 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 left operand or right operand is executed for any operator (See this for more details)
After Swapping values of x and y are 10 5
Alternate Solutions :
- C++ also provides a library function swap()
- b = (a + b) – (a = b); [Thanks to Rajat Mishra for this]
- a += b – (b = a); [Thanks to Zoran Davidovi? for this]
- a = a * b / (b = a)[Thanks to kongasricharan for this]
This article is contributed by Harshit Gupta. If you like GeeksforGeeks and would like to contribute, you can also write an article and mail your article to email@example.com. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above
- Swap three variables without using temporary variable
- Read a file line by line in Python
- Python Variables
- Private Variables in Python
- Python Scope of Variables
- Python | Unpack whole list into variables
- Python | Extract key-value of dictionary in variables
- Class or Static Variables in Python
- Global and Local Variables in Python
- Variables in Java
- Difference between Static variables and Register variables in C
- How to assign values to variables in Python and other languages
- Inserting variables to database table using Python
- Python | Set 2 (Variables, Expressions, Conditions and Functions)
- Using Variables in JShell of Java 9