Distinguish float and integer types from string

[XavierAP]

On Saturday, 9 March 2019 at 18:11:09 UTC, Jacob Shtokolov wrote:
>
> One of the task was to take a string from STDIN and detect its 
> type.
> There were a few options: Float, Integer, string and "something 
> else" (which, I think, doesn't have any sense under the scope 
> of the task).

Another std-based solution I came up with:

bool isInteger(string str)
{
     if(str.isNumeric)
     {
         try { return str.to!long == str.to!real; }
         catch(ConvException) { return false; }
     }
     else return false;
}

> I tried to use std.conv.to and std.conv.parse, but found that 
> they can't really do this. When I call `data.to!int`, the value 
> of "123.45" will be converted to int!

What compiler version are you using? I on the other hand was 
surprised that I needed the try-catch above, after having already 
checked isNumeric. The documentation claims that the conversion 
to int or long would truncate, but my compiler (v2.084.0) throws 
instead.