On 04/12/2017 00:53, Edward Diener wrote:
> In the following program, test_scanf_hex.c
>
> #include <stdio.h>
> int main()
> {
>
> const char * str = "0xa4";
> unsigned char res = 0;
>
> sscanf(str,"%hhx",&res);
>
> return (res == 0 ? 1 : 0);
> }
>
> If I compile with -std=c99 I receive:
>
> test_scanf_hex.c: In function 'main':
> test_scanf_hex.c:9:19: warning: unknown conversion type character 'h' in format [-Wformat=]
> sscanf(str,"%hhx",&res);
> ^
> test_scanf_hex.c:9:16: warning: too many arguments for format [-Wformat-extra-args]
> sscanf(str,"%hhx",&res);
> ^~~~~~
> test_scanf_hex.c:9:19: warning: unknown conversion type character 'h' in format [-Wformat=]
> sscanf(str,"%hhx",&res);
> ^
> test_scanf_hex.c:9:16: warning: too many arguments for format [-Wformat-extra-args]
> sscanf(str,"%hhx",&res);
> ^~~~~~
>
> Why is the 'hh' modifier not supported in c99 ?
I cannot reproduce this issue.
$ cat scanf.c
#include <stdio.h>
int main(int argc, char **argv)
{
unsigned char res;
if (argc > 1)
sscanf(argv[1], "%hhx", &res);
return res;
}
$ gcc-4.8 -std=c99 -O2 -Wall -Wextra scanf.c && ./a.out 10 ; echo $?
16
$ gcc-5 -std=c99 -O2 -Wall -Wextra scanf.c && ./a.out 10 ; echo $?
16
$ gcc-6 -std=c99 -O2 -Wall -Wextra scanf.c && ./a.out 10 ; echo $?
16
$ gcc-7 -std=c99 -O2 -Wall -Wextra scanf.c && ./a.out 10 ; echo $?
16
I suspect you are using a Windows port, such as mingw?
Regards.
