Print!() doesn't execute properly

Here is a piece of code:
// inside main()
// ask for user input
print!("Enter number: ");
let mut str = String::new();
std::io::stdin().read_line(&mut str);
println!("You have entered {str}");
// main function ends right here

Enter number: You have entered 4

Question: Why didn't the print! execute immediately?

You need to flush Stdout I guess.

print!("Enter number: ");
let mut str = String::new();
std::io::stdin().read_line(&mut str).unwrap();
println!("You have entered {str}");

stdout is line-buffered. println! ends with a newline, so it automatically flushes the buffer to stdout. print! doesn't automatically print a newline, so you must flush the buffer manually, as @Miiao showed.


Thanks everyone.

I also had to add " use std::io::Write; " at the top. Looks like flush() is part of Write and the Write trait had to be brought into the scope too. Thanks.

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