readln() doesn't stop to read the input.

[anonymous via Digitalmars-d]

On Saturday, 28 March 2015 at 03:07:31 UTC, jonaspm wrote:
> module main;
>
> import std.stdio;
> import std.string;
>
> int main(string[] args)
> {
>      int resp;
>      char[] p, q;
>
>      writefln("MENU DE OPCIONES");
>      writefln("1) Modus Ponens");
>      writefln("2) Modus Tollens");
>      writefln("3) Silogismo Hipotetico");
>      writefln("4) Salir");
>
> 	do{
> 	    writeln("Introduce la opcion que deseas: ");
> 	    readf(" %d", &resp);
> 	}while(resp<1 || resp>4);
>
> 	write("Write p:");
> 	readln(p);  // This is skipped. ¿?
> 	p = chomp(p);
> 	write("Write q:");
> 	readln(q);
> 	q = chomp(q);
>
>
>      writeln("p: ",p); // Doesn't write anything.
>
>      writeln("q: ",q); // Writes what you typed in the keyboard
> back on readln();
>
>
> 	return 0;
> }

The problem is that the `readf` call doesn't read the first line 
completely. It leaves the newline. The first `readln` call then 
picks up that newline and stops right there, resulting in an 
empty line.

I'm not sure how the `readf` could be changed to consume the 
newline. I tried " %d\n" and " %d ". They don't seem to do it.

But you can add a `readln();` after the `readf` call and it works.