• Cooler (6/6) Feb 20 2014 The code:
• Stanislav Blinov (3/9) Feb 20 2014 No. s may still contain data that is not convertible to int. For
• Cooler (4/14) Feb 20 2014 Is there any way to know that a string is convertible to a number
• bearophile (5/7) Feb 20 2014 I suggested to add it:
• Cooler (2/9) Feb 20 2014 Yeap. Thanks. Will wait for the enhancment.
• w0rp (16/33) Feb 20 2014 You could do this.
• Stanislav Blinov (6/10) Feb 20 2014 And what about +/- and U/L suffixes? Or, say, different base
• w0rp (5/15) Feb 20 2014 True, this doesn't cover those. Returning a
• Jesse Phillips (3/7) Feb 20 2014 Nope, integer overflow exception. Though I didn't check if it

"Cooler" <kulkin hotbox.ru> writes:

The code:

string s = "...";
if(s.isNumeric){
     auto x = parse!int(s); // Can I be sure here that parse will
not throw?
}

"Stanislav Blinov" <stanislav.blinov gmail.com> writes:

On Thursday, 20 February 2014 at 19:11:55 UTC, Cooler wrote:
 The code:

 string s = "...";
 if(s.isNumeric){
     auto x = parse!int(s); // Can I be sure here that parse will
 not throw?
 }

No. s may still contain data that is not convertible to int. For
example, "nan".

"Cooler" <kulkin hotbox.ru> writes:

On Thursday, 20 February 2014 at 19:18:15 UTC, Stanislav Blinov
wrote:
 On Thursday, 20 February 2014 at 19:11:55 UTC, Cooler wrote:
 The code:

 string s = "...";
 if(s.isNumeric){
    auto x = parse!int(s); // Can I be sure here that parse will
 not throw?
 }

 No. s may still contain data that is not convertible to int. For
 example, "nan".

Is there any way to know that a string is convertible to a number
without throwing?

"bearophile" <bearophileHUGS lycos.com> writes:

Cooler:

 Is there any way to know that a string is convertible to a 
 number without throwing?

I suggested to add it:
https://d.puremagic.com/issues/show_bug.cgi?id=6840

Bye,
bearophile

"Cooler" <kulkin hotbox.ru> writes:

On Thursday, 20 February 2014 at 19:37:08 UTC, bearophile wrote:
 Cooler:

 Is there any way to know that a string is convertible to a 
 number without throwing?

 I suggested to add it:
 https://d.puremagic.com/issues/show_bug.cgi?id=6840

 Bye,
 bearophile

Yeap. Thanks. Will wait for the enhancment.

"w0rp" <devw0rp gmail.com> writes:

On Thursday, 20 February 2014 at 19:23:28 UTC, Cooler wrote:
 On Thursday, 20 February 2014 at 19:18:15 UTC, Stanislav Blinov
 wrote:
 On Thursday, 20 February 2014 at 19:11:55 UTC, Cooler wrote:
 The code:

 string s = "...";
 if(s.isNumeric){
   auto x = parse!int(s); // Can I be sure here that parse will
 not throw?
 }

 No. s may still contain data that is not convertible to int. 
 For
 example, "nan".

 Is there any way to know that a string is convertible to a 
 number
 without throwing?

You could do this.

import std.stdio;
import std.algorithm: all;
import std.ascii: isDigit;

void main(string[] args) {
      writeln("123".all!isDigit); // true
      writeln("12x".all!isDigit); // false
}

Combine the "all" algorithm which returns true if everything in a
range matches a predicate and use "isDigit" as the predicate
which returns true if the character is an ascii digit.

if (s.length > 0 && s.all!isDigit) {
      // Never throws now.
      auto x = parse!int(s);
}

"Stanislav Blinov" <stanislav.blinov gmail.com> writes:

On Thursday, 20 February 2014 at 19:46:35 UTC, w0rp wrote:

 if (s.length > 0 && s.all!isDigit) {
      // Never throws now.
      auto x = parse!int(s);
 }

And what about +/- and U/L suffixes? Or, say, different base 
(i.e. hexadecimal)?

It would be way more beneficial if Phobos' parse (or some 
additional function) returned some kind of Optional. Maybe a D 
implementation of Andrei's Expected<T>?

"w0rp" <devw0rp gmail.com> writes:

On Thursday, 20 February 2014 at 19:58:10 UTC, Stanislav Blinov
wrote:
 On Thursday, 20 February 2014 at 19:46:35 UTC, w0rp wrote:

 if (s.length > 0 && s.all!isDigit) {
     // Never throws now.
     auto x = parse!int(s);
 }

 And what about +/- and U/L suffixes? Or, say, different base 
 (i.e. hexadecimal)?

 It would be way more beneficial if Phobos' parse (or some 
 additional function) returned some kind of Optional. Maybe a D 
 implementation of Andrei's Expected<T>?

True, this doesn't cover those. Returning a
Maybe/Option/Nullable/Whatever type from another function may be
better.

"Jesse Phillips" <Jesse.K.Phillips+D gmail.com> writes:

On Thursday, 20 February 2014 at 19:46:35 UTC, w0rp wrote:
 if (s.length > 0 && s.all!isDigit) {
      // Never throws now.
      auto x = parse!int(s);
 }

Nope, integer overflow exception. Though I didn't check if it 
would actually through that, but it should.