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From: Keith Thompson <Keith.S.Thompson+u@gmail.com>
Newsgroups: comp.lang.c
Subject: Re: Automatic strings without malloc
Date: Wed, 17 Nov 2021 11:22:37 -0800
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David Brown <david.brown@hesbynett.no> writes:
> On 17/11/2021 16:36, Malcolm McLean wrote:
>> On Wednesday, 17 November 2021 at 15:34:50 UTC, Scott Lurndal wrote:
>>> pozz <pozz...@gmail.com> writes: 
>>>> Many times I need to construct a string through a call to sprintf and 
>>>> pass it to an external function. 
>>>>
>>>> char s[32]; 
>>>> sprintf(s, "Hi %s, today is %d/%d/%d", yourname, day, month, year); 
>>>> lcd_write(s);
>>> One might consider using 'snprintf' instead of 'sprintf'; it is a bit safer. 
>>>
>> It depends whether wrong results are better or worse than no results.
>
> Generally, a truncated string on the output is better than a stack
> overflow with your embedded system crashing or going wild.  But your
> needs may vary.

Sure, truncation is probably better than undefined behavior, but
depending on the context it might not be *much* better.

For a small LCD display, truncation is probably the best fallback
(followed by thinking about how to make the message fit).  On the other
hand, truncating "rm -rf /home/user/temp_dir" to "rm -rf /home/user" is
likely to be far worse than crashing the program.

There's no general rule other than that you should always *think*
about what will/should happen if there's not enough room in the target
array.

-- 
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
Working, but not speaking, for Philips
void Void(void) { Void(); } /* The recursive call of the void */