GCC supports this as an extension.
Mixing declarations and code is allowed in C99 and C23
will also allow placing labels before declarations and at
the end of a compound statement. GCC supports all this
also in earlier language modes.
See:
https://gcc.gnu.org/onlinedocs/gcc/Mixed-Labels-and-Declarations.html
You will get the warnings with -pedantic.
Martin
Am Donnerstag, dem 19.10.2023 um 07:39 -0400 schrieb Eric Sokolowsky via Gcc:
> I am using gcc 13.2 on Fedora 38. Consider the following program.
>
> #include <stdio.h>
> int main(int argc, char **argv)
> {
> printf("Enter a number: ");
> int num = 0;
> scanf("%d", &num);
>
> switch (num)
> {
> case 1:
> int a = num + 3;
> printf("The new number is %d.\n", a);
> break;
> case 2:
> int b = num - 4;
> printf("The new number is %d.\n", b);
> break;
> default:
> int c = num * 3;
> printf("The new number is %d.\n", c);
> break;
> }
> }
>
> I would expect that gcc would complain about the declaration of
> variables (a, b, and c) within the case statements. When I run "gcc
> -Wall t.c" I get no warnings. When I run "g++ -Wall t.c" I get
> warnings and errors as expected. I do get warnings when using MinGW on
> Windows (gcc version 6.3 specifically). Did something change in 13.2?
>
> Eric
