Rust: Increment counter by specified amount

Last update on June 07 2025 13:04:09 (UTC/GMT +8 hours)

Write a Rust function that accepts a mutable reference to a counter variable and increments it by a specified amount.

Sample Solution:

Rust Code:

// Define a function named 'increment_counter' that takes a mutable reference to a counter variable and increments it by a specified amount
fn increment_counter(counter: &mut i32, amount: i32) {
    *counter += amount; // Increment the counter by the specified amount
}

fn main() {
    let mut counter = 0; // Define a mutable counter variable initialized with 0
    let amount = 5; // Define the amount by which the counter should be incremented

    increment_counter(&mut counter, amount); // Call the 'increment_counter' function with a mutable reference to the counter variable

    println!("Counter after increment: {}", counter); // Print the value of the counter after incrementing it
}

Output:

Counter after increment: 5

Explanation:

Here's a brief explanation of the above Rust code:

'fn increment_counter(counter: &mut i32, amount: i32) { ... }': This is a function named 'increment_counter' that takes two parameters: a mutable reference to a counter variable ('counter') and the amount by which the counter should be incremented ('amount'). The counter variable is of type 'i32', a 32-bit integer.
'*counter += amount;': This line increments the value of the 'counter' by adding the specified 'amount' to it. The '*' operator is used to dereference the mutable reference and modify the value it points to.
'fn main() { ... }': This is the program's entry point.
'let mut counter = 0;': This line defines a mutable counter variable named 'counter' and initializes it with the value '0'.
'let amount = 5;': This line defines the amount by which the counter should be incremented.
'increment_counter(&mut counter, amount);': This line calls the 'increment_counter' function with a mutable reference to the 'counter' variable and the specified 'amount'. The '&mut' operator creates a mutable reference to the 'counter' variable.
'println!("Counter after increment: {}", counter);': This line prints the value of the 'counter' variable after it has been incremented.

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