Macro log 

macro_rules! log {
    ($($arg:tt)*) => { ... };
}

A logging macro that prints the value to stdout, with a newline.

This macro is a more gas-efficient alternative to regular println! statements. It evaluates the given expression and writes its display representation to standard output, followed by a newline.

Examples

let value = 42;
log!("{}", value);  // Prints: 42\n
log!("The answer is: {}", value);  // Prints: The answer is: 42\n

Notes

This macro requires that the expression’s type implements the Display trait.