What is the difference between these codes?

code review
1

Hello,
both of these codes print Hello, World!, but what is the difference between them and which one is more correct?

fn main ()
{
print!("Hello, World!");
}

And

fn main ()
{
print!("{}", "Hello, World!");
}

Is {} mandatory?

Please answer this question briefly.

Thank you.

2

The {}is intended as a place holder for any variables you want to print in your output string. If you have no variables, as in this case, then you don't need the braces.

1 Like
3

Hello,
Thank you so much for your reply.
So, if I have a variable that holds a string like "Hello, World!", then my code must be:

print!("{}", varibale);

Am I right?

4

Yep.

1 Like
5

Hello,
Thank you so much for your reply.

6

Yes. And in recent Rust releases you can also do this:

println!("{variable}");`

Which is nice when you want to say something like this, for variables x, y and z:

println!("x = {x}, y = {y}, z = {z}");

rather than:

println!("x = {}, y = {}, z = {}", x, y, z);
1 Like