writef

[Jason House]

Claus D.  Volko wrote:

> Hi,
> 
> I'm currently writing a D tutorial for people new to programming, and I've
> experienced some strange behavior:
> 
> The following program works as intended:
> 
> // The "Hello World!" program
> 
> import std.stdio;
> import std.c.stdio;
> 
> void main ()
> {
>   int i;                                    // Variable definition
>   i = 200;                                  // Assignment
>   writefln ("Hello World!");                // Function call
>   writefln ("The value of i is ", i, ".");  // Function call
>   getch ();                                 // Function call
> }
> 
> But if I replace
> 
> writefln ("The value of i is ", i, ".");
> 
> with
> 
> writef ("The value of i is ", i, ".");
> 
> the output of "The value of i is 200." happens only after the keypress.
> Unfortunately, I haven't been able to find any documents about writef on
> the Net which could have explained why it's like this, or whether it's a
> bug. Therefore I'm posting my question to this newsgroup: Why?

I'm going to guess the answer is flushing.  I suspect writefln will flush the output following the implied newline, but writef won't.  This is similar to most console output libraries I use.  For example, C++ uses std::endl for a flushed newline and "\n" for just a newline without flushing.