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Pass by Reference

Understand how to pass arguments by reference in Rust functions. This lesson demonstrates mutable references, dereferencing, and updating values within a function to manage data effectively.

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Arguments Pass by Reference

When we want the called function to make changes to the parameters such that the changes are seen by the calling function when the call returns. The mechanism to do this is called pass arguments by reference.

Syntax

The general syntax of passing arguments by reference is:

Example

The following example makes a function square() that takes a number n which is being passed by reference as a parameter to the function and prints the square of the function within the function.

Rust 1.40.0
fn square(n:&mut i32){
  *n = *n * *n;
  println!("The value of n inside function : {}", n);
}  
fn main() {
  let  mut n = 4;
  println!("The value of n before function call : {}", n);
  println!("Invoke Function");
  square(&mut n);
  println!("The value of n after function call : {}", n);
}
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