public inbox for bitcoindev@googlegroups.com
 help / color / mirror / Atom feed
From: Wladimir <laanwj@gmail.com>
To: Thomas Zander <thomas@thomaszander.se>
Cc: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>
Subject: Re: [Bitcoin-development] Malleable booleans
Date: Tue, 14 Oct 2014 10:04:20 +0200	[thread overview]
Message-ID: <CA+s+GJBvOH9cW_yaK7ZEDUYznDe=KeoMYMZ3KF=P503JceWFeg@mail.gmail.com> (raw)
In-Reply-To: <201410140927.36252.thomas@thomaszander.se>

On Tue, Oct 14, 2014 at 9:27 AM, Thomas Zander <thomas@thomaszander.se> wrote:
> On Tuesday 14. October 2014 04.34.16 Pieter Wuille wrote:
>> This means that scripts that use booleans as inputs will be inherently
>> malleable.
>
> I've ran into this issue in C++ often enough,
> a funny example is assigning "2" to a native c++ bool and then you can do a
>  if (myBool == true)
>  else if (myBool == false)
> and neither of them will hit.

Off topic nit: I think you're confused with custom BOOL typedefs in C?
C++ booleans are protected against this (C++ standard §4.7/4 according
to Google).:

```
#include <stdio.h>

int main()
{
    bool myBool;
    myBool = 2;
    if (myBool == true)
        printf("It is true!\n");
    else if (myBool == false)
        printf("It is false!\n");
    else
        printf("It is something else!\n");
}
```

Prints 'It is true'. You can also use bool(something) as equivalent of
`x != 0`; as in `assert(bool(2) == true);`.

Wladimir



  parent reply	other threads:[~2014-10-14  8:04 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-10-14  2:34 [Bitcoin-development] Malleable booleans Pieter Wuille
2014-10-14  2:45 ` Gregory Maxwell
2014-10-14  7:27 ` Thomas Zander
2014-10-14  7:52   ` Gregory Maxwell
2014-10-14  8:04   ` Wladimir [this message]
2014-10-14  8:09 ` Peter Todd
2014-10-14 18:54   ` Pieter Wuille
2014-10-14 19:45     ` Peter Todd

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CA+s+GJBvOH9cW_yaK7ZEDUYznDe=KeoMYMZ3KF=P503JceWFeg@mail.gmail.com' \
    --to=laanwj@gmail.com \
    --cc=bitcoin-development@lists.sourceforge.net \
    --cc=thomas@thomaszander.se \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox