Swap Without Temp Variable in C, C++, Java & Python – Code with Explanation & Examples in Short and Simple

   

C Program

/* C - Swap two numbers without temp variable */
#include <stdio.h>

int main() {
    int a, b;
    if (scanf("%d %d", &a, &b) != 2) return 0;
    a = a + b;
    b = a - b;
    a = a - b;
    printf("%d %d\n", a, b);
    return 0;
}

C Output

Input:
5 9
Output:
9 5

C++ Program

// C++ - Swap without temp variable
#include <iostream>
using namespace std;

int main() {
    int a, b;
    if (!(cin >> a >> b)) return 0;
    a ^= b;
    b ^= a;
    a ^= b;
    cout << a << " " << b << "\n";
    return 0;
}

C++ Output

Input:
12 7
Output:
7 12

JAVA Program

// Java - Swap without temp variable
import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        if (!sc.hasNextInt()) return;
        int a = sc.nextInt(), b = sc.nextInt();
        a = a * b;
        b = a / b;
        a = a / b;
        System.out.println(a + " " + b);
    }
}

JAVA Output

Input:
4 15
Output:
15 4

Python Program

# Python - Swap without temp variable
a, b = map(int, input().split())
a, b = b, a
print(a, b)

Python Output

Input:
20 35
Output:
35 20

In-Depth Learning – Entire Concept in Paragraphs

Example:

Exchanging without a temporary variable implies interchanging two variable values without employing a third storage area. The most standard methods to accomplish this are:

Addition and subtraction method: a = a + b; b = a - b; a = a - b;

Multiplication and division approach: a = a * b; b = a / b; a = a / b; (only when both are non-zero and there is no overflow)

XOR approach: a ^= b; b ^= a; a ^= b; (bitwise operation, immune to arithmetic overflow but applies only to integers)

In Python, it is possible to swap through tuple unpacking in one line: a, b = b, a.

Real-Life Analogy:

Suppose you and your friend each possess a cup of coffee, and you wish to exchange cups without having a third cup sitting idle. One way is to fill each other's partially and use the surplus to get there — the "addition/subtraction" approach. A second is with an ingenious trick (e.g., flipping them in your palms and voilà. — magic happens) — the "XOR" approach. Both accomplish the task without requiring an additional vessel.

Why It Matters:

This exercise educates you on in-place value manipulation, arithmetic properties, and bit operations. It's an excellent exercise to practice logical thinking, particularly learning how operations can be reversed without losing data. Swapping without temp is typically employed in tight memory environments or as a micro-optimization hack, although in contemporary programming, readability tends to trump micro-optimizations.

Learning Insights:

This exercise solidifies your grasp of operator precedence, arithmetic overflow danger, and integer vs. floating point behavior. The XOR technique is particularly fascinating due to its operation at the binary level and being termed a "classic interview puzzle." In Python, tuple unpacking is not only neater but also circumvents dangers of arithmetic overflow or division-by-zero exceptions.

Interview and Project Relevance:

Interviewers tend to use the "swap without temp" problem to assess whether you can think creatively and know how variables hold values. The XOR approach demonstrates awareness of bitwise operations, and the math approaches evaluate math and overflow understanding. For embedded systems or low-level programming with registers being scarce, in-place swapping may be a viable option.

SEO-friendly conclusion:

This tutorial illustrates several methods for swapping two integers without an extra variable, with functional C, C++, Java, and Python code. All the examples cover addition-subtraction, multiplication-division, bitwise XOR, and Python's tuple unpacking methods. The description includes explanations of how each approach works, advantages and disadvantages, handling overflows, and under what circumstances they can be applied in interviews or in the real world. Knowing these swap methods enhances problem-solving efficiency, memory operation awareness, and preparation for traditional coding interview questions.