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Re: labels at the end of a function

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Thiago Adams <thiago.adams@gmail.com> writes:
> On Monday, August 29, 2022 at 10:36:05 PM UTC-3, Lynn McGuire wrote:
>> I just found out that a label at the end of a c/c++ function must have 
>> an executable statement after it. 
>> 
>> int aMethod () 
>> { 
>> int aFakeVar = 0; 
>> 
>> goto aLabel; 
>> 
>> aLabel: 
>> 
>> aFakeVar++; 
>> } 
>> 
>> Is there any way to get around the requirement of the executable 
>> statement after the label ? 
>> 
>> Thanks, 
>> Lynn
>
> aLabel:;
>
> empty ; 

One difference between C and C++ is that C++ allows a label to precede a
declaration, but C doesn't.  This is a side effect of the way C and C++
express the ability to mix declarations and statements within a block.
In C, a compound-statement contains a list of block-items, where a
block-item is a declaration or a statement (possibly a
labeled-statement).  In C++, a compound-statement contains a list of
statements, but a declaration in a block is syntactically a
declaration-statement.

C23 (as of N3047) permits labels anywhere in a block, including on a
declaration and (unlike C++) just before the closing "}".  It redefines
a block-item to be any of a declaration, an unlabeled-statement, or a
label.

{
    LABEL1:             // Invalid in C17, valid in C23 and C++
    int n = 42;
    LABEL2:             // Valid in C and C++
    printf("n = %d\n", n);
    LABEL3:;           // Valid in C and C++
    LABEL3:            // Valid in C23, invalid in C17 and C++
}

-- 
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 */

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Thread

labels at the end of a function Lynn McGuire <lynnmcguire5@gmail.com> - 2022-08-29 20:35 -0500
  Re: labels at the end of a function Thiago Adams <thiago.adams@gmail.com> - 2022-08-29 18:47 -0700
    Re: labels at the end of a function Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-08-29 21:50 -0700
      Re: labels at the end of a function Kaz Kylheku <480-992-1380@kylheku.com> - 2022-08-30 05:52 +0000
  Re: labels at the end of a function Sam <sam@email-scan.com> - 2022-08-29 22:42 -0400
    Re: labels at the end of a function Anton Shepelev <anton.txt@g{oogle}mail.com> - 2022-08-30 12:46 +0300
      Re: labels at the end of a function Juha Nieminen <nospam@thanks.invalid> - 2022-08-30 11:20 +0000
      Re: labels at the end of a function Opus <ifonly@youknew.org> - 2022-08-30 20:15 +0200
  Re: labels at the end of a function Ike Naar <ike@sdf.org> - 2022-08-30 05:50 +0000
    Re: labels at the end of a function Elephant <diespammer@yahoo.it> - 2022-08-30 10:14 +0200
  Re: labels at the end of a function Bo Persson <bo@bo-persson.se> - 2022-08-30 09:14 +0200
  Re: labels at the end of a function scott@slp53.sl.home (Scott Lurndal) - 2022-08-30 13:21 +0000
    Re: labels at the end of a function gazelle@shell.xmission.com (Kenny McCormack) - 2022-08-30 14:44 +0000
      Re: labels at the end of a function Lynn McGuire <lynnmcguire5@gmail.com> - 2022-08-30 16:08 -0500
        Re: labels at the end of a function Anton Shepelev <anton.txt@gmail.com> - 2022-08-31 01:04 +0300
  Re: labels at the end of a function Lynn McGuire <lynnmcguire5@gmail.com> - 2022-08-30 20:29 -0500

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