How to swap two variables?

swap two numbers without using third variable in c#
how to swap two variables in java
swap the values of two variables
swap two numbers in python
swap two numbers without using third variable in python
swapping of two numbers in c++
c program to swap two numbers using functions
swap two numbers in java

What is the closest equivalent Rust code to this Python code?

a, b = 1, 2
a, b = b, a + b

I am trying to write an iterative Fibonacci function. I have Python code I want to convert to Rust. Everything is fine, except for the swap part.

def fibonacci(n):
    if n < 2:
        return n
    fibPrev = 1
    fib = 1
    for num in range(2, n):
        fibPrev, fib = fib, fib + fibPrev
    return fib

C Program to Swap Two Numbers, Swap Numbers Using Temporary Variable. #include<stdio.h> int main() { double first, second, temp; printf("Enter first number: "); scanf("%lf", &first); printf("Enter� Given two variables x and y, write a Python program to swap their values. Let’s see different methods in Python to do this task. Method 1: Using Naive approach The most naive approach is to store the value of one variable(say x) in a temporary variable, then assigning the variable x with the value of variable y.

In addition, a better way to implement the Fibonacci sequence in Rust is using the Iterator trait:

// Iterator data structure
struct FibIter(u32, u32);

// Iterator initialization function
fn fib() -> FibIter {
    FibIter(0u32, 1u32)
}

// Iterator trait implementation
impl Iterator for FibIter {
    type Item = u32;
    fn next(&mut self) -> Option<u32> {
        *self = FibIter(self.1, self.1 + self.0);
        Some(self.0)
    }
}

fn main() {
    println!("{:?}", fib().take(15).collect::<Vec<_>>());
}

See The Rust Programming Language chapter on iterators.

Python Program to Swap Two Variables, Source Code: Using a temporary variable. # Python program to swap two variables x = 5 y = 10 # To take inputs from� Write a Java program to swap two variables. Java: Swapping two variables. Swapping two variables refers to mutually exchanging the values of the variables. Generally, this is done with the data in memory. The simplest method to swap two variables is to use a third temporary variable : define swap(a, b) temp := a a := b b := temp

I'm surprised none of the answers mention the XOR-swap:

fibPrev ^= fib;
fib ^= fibPrev;
fibPrev ^= fib;

This is a well-known way to swap two values without using a temporary variable or risking integer overflow.

Note that with modern optimizing compilers, in most cases it's better from performance standpoint to just use a temporary variable (see link in the comment by trentcl). There are, however, some use cases for the XOR-swap, the linked Wikipedia article provides a decent overview of its pros and cons.

Interestingly enough, if you were to implement a XOR-swap as a function in rust, you don't need to check if you're trying to swap a variable with itself (in which case you'll end up with it being set to zero due to the properties of a XOR operation). Compare swap implementations in rust:

fn swap(a: &mut i32, b: &mut i32) {
    *a ^= *b;
    *b ^= *a;
    *a ^= *b;
}

and C++:

void swap(int& a, int& b) {
    if (&a == &b) return; // Avoid swapping the variable with itself
    a ^= b;
    b ^= a;
    a ^= b;
}

If you try to call swap like this in rust:

let mut a = 42;
swap(&mut a, &mut a);

You will get a compilation error:

error[E0499]: cannot borrow `a` as mutable more than once at a time
  --> src/main.rs:27:18
   |
27 |     swap(&mut a, &mut a);
   |     ---- ------  ^^^^^^ second mutable borrow occurs here
   |     |    |
   |     |    first mutable borrow occurs here
   |     first borrow later used by call

Java exercises: Swap two variables, Generally, this is done with the data in memory. The simplest method to swap two variables is to use a third temporary variable : define swap(a, b)� Swapping variables using bitwise XOR operator has limitations: you can swap only integers. 5. Conclusion. JavaScript offers a bunch of good ways to swap variables, with and without additional memory. The first way, which I recommend for daily use, is swapping variables by applying destructuring assignment [a, b] = [b, a]. It’s a short and

Swapping two variable value without using third variable, Using the xor swap algorithm void xorSwap (int* x, int* y) { if (x != y) { //ensure that memory locations are different *x ^= *y; *y ^= *x; *x ^= *y; } }. PHP: Swapping two variables. Swapping two variables refers to mutually exchanging the values of the variables. Generally, this is done with the data in memory. The simplest method to swap two variables is to use a third temporary variable : define swap(a, b) temp := a a := b b := temp Sample Solution: -Code : Swap two numbers using a third

C program to swap two numbers, If the program has two variables a and b where a = 4 and b = 5, after swapping them, a = 5, b = 4. In the first C program, we use a temporary variable to swap two � Python Program to Swap Two Variables In this example, you will learn to swap two variables by using a temporary variable and, without using temporary variable. To understand this example, you should have the knowledge of the following Python programming topics:

Python swap two Variables, In computer programming, swapping two variables specifies the mutual exchange of values of the variables. It is generally done by using a temporary variable. C Program to Swap Two Numbers In this example, you will learn to swap two numbers in C programming using two different techniques. To understand this example, you should have the knowledge of the following C programming topics:

Comments
  • Please make sure to read The Rust Programming Language. It covers lots of introductory topics.
  • @Shepmaster, spent some time reading about swap and replace but not sure if what I need here.
  • can you elaborate on when someone would want to change things in place vs re-binding the variables? Also, what's wrong with creating new bindings? Not efficient?
  • @No_name You can't re-bind in a loop (well, you can, but the new values will be lost on the next iteration). So for example it can't be (directly) used for calculating the factorial.
  • It's probably not mentioned because it's a trick that assumes registers are more valuable than instructions (they aren't), and trades readability for a smug sense of superiority. It's a brainteaser, not something you should ever write in real code. Furthermore, this doesn't even really solve the OP's problem; as Shepmaster's answer points out, it's not concise to do the addition and swap in one step, as OP's Python code does (even if you just use mem::swap).
  • To avoid falling into the same trap, I should say registers probably aren't more valuable than instructions. The point is that you need to know a lot about the computer that will be running your program in order to make intelligent decisions about whether XOR-swap is ever "better" than using a temporary, so if unsure, you should stick with the code that's dead simple.
  • Thanks for the comparison, and it's a fair point that just using a temporary gets optimized better than a XOR-swap; noted in the answer. However, it's not any more of a brainteaser than any other algorithm, and it still has valid use cases, such as cryptographic systems. Also, in order to make an informed decision on which algorithm to choose, you first need to know that they exist.
  • How is it not a brainteaser? You need to have seen it before to have any hope of knowing what it does. It has a subtle gotcha (albeit one that is mostly mitigated by the semantics of &mut references, as you note). It has a simple and obvious alternative that any fool can read and is faster. You'd be a fool to ever do an XOR-swap in real code, except maybe on a register starved architecture (and then only after profiling to prove it even makes a difference).
  • Either way I'm not sure why you are so triggered by this answer, especially since I've already added the note that the simple temp-variable swap is better to be used in the real-life code.