Rust Program to Convert Decimal to Binary (Using Bitwise, Loop, Recursion, and More)

Introduction

Rust is a modern systems programming language that emphasizes performance, memory safety, and concurrency.

While it’s widely used for low-level development, Rust can also be leveraged for data conversion tasks like decimal to binary conversion with multiple approaches — bitwise operations, recursion, and loop-based methods.

 

Problem Statement

Write multiple Rust programs to convert decimal numbers into binary using various methods such as bitwise manipulation, while loops, recursion, and more.

 

Use Cases

• Binary data handling in embedded systems.

• Performing low-level data transformations.

• Learning bitwise operations and memory-efficient logic.

• Creating console tools for educational or debugging purposes.

 

Method 1: Using Bitwise Operator

// Program 1: Convert Decimal to Binary using Bitwise Operator
fn bitwise_binary(mut num: u32) -> String {
    let mut result = String::new();
    let mut started = false;
    for i in (0..32).rev() {
        let bit = (num >> i) & 1;
        if bit == 1 {
            started = true;
        }
        if started {
            result.push_str(&bit.to_string());
        }
    }
    if result.is_empty() {
        result.push('0');
    }
    result
}

fn main() {
    println!("Binary (45): {}", bitwise_binary(45));
}

 

Output

 

Explanation

• Shifts bits from the highest to the lowest.

• Starts appending bits when the first 1 is encountered.

 

Method 2: Using Recursion

// Program 2: Convert Decimal to Binary using Recursion
fn recursive_binary(num: u32) -> String {
    if num == 0 {
        return "".to_string();
    }
    let prev = recursive_binary(num / 2);
    format!("{}{}", prev, num % 2)
}

fn main() {
    let result = recursive_binary(18);
    println!("Binary (18): {}", if result.is_empty() { "0".to_string() } else { result });
}

 

Output

 

Explanation

• Recursively divides the number and builds the binary string.

• Handles the base case for 0.

 

Method 3: Using While Loop and Vec

// Program 3: Convert Decimal to Binary using While Loop
fn loop_binary(mut num: u32) -> String {
    if num == 0 {
        return "0".to_string();
    }
    let mut result = Vec::new();
    while num > 0 {
        result.push((num % 2).to_string());
        num /= 2;
    }
    result.reverse();
    result.join("")
}

fn main() {
    println!("Binary (22): {}", loop_binary(22));
}

 

Output

 

Explanation

• Collects binary digits in a vector.

• Reverses them to get the correct order.

 

Method 4: Using Format Macro (Built-in)

// Program 4: Convert Decimal to Binary using Built-in format!
fn builtin_format(num: u32) -> String {
    format!("{:b}", num)
}

fn main() {
    println!("Binary (64): {}", builtin_format(64));
}

 

Output

 

Explanation

• Rust’s format! macro supports base-2 ({:b}) formatting.

• Simple and concise.

 

Method 5: Custom Function with Manual Stack Simulation

// Program 5: Convert Decimal to Binary using Manual Stack Simulation
fn stack_simulation(mut num: u32) -> String {
    let mut stack = vec![];
    while num > 0 {
        stack.push((num % 2).to_string());
        num /= 2;
    }
    stack.reverse();
    stack.join("").or("0".to_string())
}

fn main() {
    println!("Binary (11): {}", stack_simulation(11));
}

 

Output

 

Explanation

• Simulates stack push and reverse behavior.

• Returns "0" for zero input.

 

Method 6: Using Collect and Iterators

// Program 6: Convert Decimal to Binary using Functional Style
fn iterator_method(mut num: u32) -> String {
    if num == 0 {
        return "0".to_string();
    }
    let mut bits = vec![];
    while num > 0 {
        bits.push((num % 2).to_string());
        num /= 2;
    }
    bits.iter().rev().cloned().collect()
}

fn main() {
    println!("Binary (9): {}", iterator_method(9));
}

 

Output

 

Explanation

• Uses functional approach with .iter().rev().cloned().collect().

• Provides clean and idiomatic Rust code.

 

Conclusion

We explored six different Rust programs to perform decimal to binary conversion using recursion, bitwise operations, loop-based methods, and built-in formatting. Rust’s expressive syntax and memory safety guarantees make these implementations efficient and reliable.