How to avoid throwing an exceptions for a built-in function?

[k-five via Digitalmars-d-learn]

On Wednesday, 10 May 2017 at 21:19:21 UTC, Stanislav Blinov wrote:
> On Wednesday, 10 May 2017 at 15:35:24 UTC, k-five wrote:
>> On Wednesday, 10 May 2017 at 14:27:46 UTC, Stanislav Blinov
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> I don't understand. If you don't want to take care of 
> exceptions, then you just don't do anything, simply call 
> to!int(str).

Well I did that, but when the string is a valid type like: "10" 
there is no problems. But when the string is not valid, like: 
"abc", then to! function throws an exception.

Why I do not want to take care of that? Because I just need the 
value, if the string is valid, otherwise no matter what the value 
of string is.

First I just wrote:
index = to!int( user_apply[ 4 ] );

And this code is a part of a command-line program and the user 
may enter anything. So, for a valid string:
./program '10'   // okey

but for:
./program 'non-numerical' // throws an exception an 10 lines of 
error appear on the screen( console )

I just want to silent this exception. Of course it is useful for 
handling when someone wants to. But in my code I no need to 
handle it. So I want to silent that, without using try{}catch(){} 
block. I just wondered about try-catch and I want to know may 
there would be a better way instead of a dummy try-catch block.

Thanks for replying and mentioning. And I am sorry, since I an 
new in English Writing, if you got confuse.