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From: bart <bc@freeuk.com>
Newsgroups: comp.lang.c
Subject: Re: Integral types and own type definitions (was Re: Suggested method
 for returning a string from a C program?)
Date: Sat, 29 Mar 2025 18:20:37 +0000
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On 29/03/2025 17:25, Janis Papanagnou wrote:
> On 26.03.2025 23:15, Keith Thompson wrote:
>> [ dyadic and monadic minus operations, and minus sign at literals ]
>>
>> I don't know of any language that uses "-" for both negation (prefix,
>> one operand) and subtraction (infix, two operands) and treats -5
>> as a single token rather than a unary minus operator applied to the
>> constant/literal "5".
> 
> I as well don't know. It may simplify things if the '-' is detached
> from a numeric positive literal, especially for numeric expressions.
> 
> There's certainly cases where a signed numeric token is appropriate,
> thinking (for example) about a CONST declaration in Pascal, like
>   CONST a = -5;  here you don't have expressions, just the primitive
> type literals.[*]
> 
> The point why I think that a signed literal as entity may be useful
> is that it's a static (compile time) property; -5 is in that respect
> different from -x, the negation operation. A negative constant does
> not "cost" a run-time operation.
> 
> Given what we recently discussed about a division by a constant,
> where compilers (may) handle expressions by pre-calculating the
> reciprocal for run-time efficiency, it's not that clear to me that
> it matters either way.
> 
> I suppose it's a question of whether it complicates syntax definition
> or parsing.



Having a single token like '-1234' is pointless. Most languages allow 
you to add parentheses like '-(1234)' which must give the exact same 
result.

And many also reduce expressions like '1234+1' to '12345' at compile 
time. In this case you'd want '-(1234+1)' to be equivalent to '-1235'.

Or there may be a named alias 'X' for 1234, and later write '-X'.

So there is no advantage to it, except possibly in the special case 
where the N in -N is something like INT_MIN, as N could have a different 
type.