• Sam Hu (52/52) Apr 10 2009 Hello everybody ,
• Kagamin (1/1) Apr 10 2009 may be your 4 goes in next line?
• Gide Nwawudu (19/71) Apr 10 2009 There is a trailing newline in the input, use the chomp function to
• Kagamin (2/8) Apr 10 2009 No
• Sam Hu (1/1) Apr 12 2009 Thanks.It works now.

Sam Hu <samhudotsamhu gmail.com> writes:

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

Kagamin <spam here.lot> writes:

may be your 4 goes in next line?

Gide Nwawudu <gide btinternet.com> writes:

On Fri, 10 Apr 2009 05:55:57 -0400, Sam Hu <samhudotsamhu 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

Kagamin <spam here.lot> writes:

Gide Nwawudu Wrote:

 [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);
 
 ?

No

Sam Hu <samhudotsamhu gmail.com> writes:

Thanks.It works now.