[SOLVED] How to pretty-print inlined variables when formatting strings

How to pretty-print inlined variables when formatting strings

Normally one can print strings the following way: println!("{:#?}", foo) where the {:#?} syntax will make a pretty-print of the value. But I know it's also possible to inline the variable directly in the string between the curly braces, instead of listing it as a second argument to the macro, like so: println!("{foo}").

My question is - can I combine the pretty-print syntax and inlining the variable in the string?

I found out about the shorthand syntax from clippy's docs, but I couldn't find (or understand) how to combine it with pretty-print (if it's at all possible).

Solution

Simply place the variable name before the colon:

fn main() {
    let foo = 3;
    println!("{foo:#?}");
}

Note:

:#? is pretty-printed Debug output
:? is normal Debug output
no modifier is Display output

Display is for user-facing output

Debug is for output when debugging, also used for panic messages