Convert from console input
Gide Nwawudu
gide at btinternet.com
Fri Apr 10 06:48:17 PDT 2009
On Fri, 10 Apr 2009 05:55:57 -0400, Sam Hu <samhudotsamhu at gmail.com>
wrote:
>Hello everybody ,
>
>I'am learning D2.028+Phobos and wrote a excise which purpose is to write a generic method which an retrieve the console input with desired type.Say if I want the user to input an integer to the console,or a double to the console,just write below code:double salary=askfor!(double);
>Below is my attemp :
>
>askForInput.d
>module askForInput;
>
>import std.stdio;
>import std.conv;
>import std.c.stdlib;
>
>T askfor(T)()
>{
> char[]msg=cast(char[])"Please enter ";
> char[] temp;
> static if(is(T==int) || is(T== long ))
> temp=cast(char[])"an integer";
> else static if(is(typof(T[])==char[])|| is(typeof(T[])==dchar[]) || is(typeof(T[])==wchar[]))
> temp=cast(char[])"a string";
> else static if(is(typeof(T)== short)|| is(typeof(T)==float)|| is(typeof(T)==double))
> temp=cast(char[])"a decimal";
> char[] retval=msg~temp~" :";
> writef(retval);
>
>
> //try
> //{
> char[] input=cast(char[])readln;
> return to!(T)(input);
> //}
> //catch(ConvError whatever)
> //{
> // writefln("Cannot convert.Error occurred.");
>
> // return T.init;
> //}
>
>}
>int main(char[][] args)
>{
> int test=askfor!(int);
> writefln("you entered %d",test);
>
> getchar;
>
> return 0;
>
>}
>
>It compiled but threw an ConvError when running:
>
>D:\Laguage\Dex>dmd askforinput.d
>
>D:\Laguage\Dex>askforinput
>Please enter an integer :4
>std.conv.ConvError: conversion Can't convert value `
>' of type const(char)[] to type int
>
>D:\Laguage\Dex>
>
>I have no clue why the convertion is not permitted.Could anybody here help me?Thanks so much!
>
>Regards,
>Sam
There is a trailing newline in the input, use the chomp function to
remove it.
import std.stdio;
import std.conv;
import std.string;
void main() {
char[] input=cast(char[])readln;
writefln("'%s'",input);
input = chomp(input);
writefln("'%d'",to!(int)(input));
}
[OT] Should chomp be defined as
void chomp(C)(ref C[] s, in C[] delimiter = null);
- instead of -
C[] chomp(C)(C[] s, in C[] delimiter = null);
?
Gide
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