Re: [PATCH v2] regex.3: Add example program

["Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>]

On 10/17/20 3:37 PM, Alejandro Colomar wrote:
> Oops,  I should've used \e instead of \\ (see below).
> Please fix that :)

Applied and fixed. Thanks Alex!

Cheers,

Michael

> Alex
> 
> On 10/17/20 3:27 PM, Alejandro Colomar wrote:
>> $ gcc -Wall -Wextra -Werror -pedantic regex.c -o regex
>> $ ./regex.3
>> String = "1) John Driverhacker;
>> 2) John Doe;
>> 3) John Foo;
>> "
>> Matches:
>> #0:
>> offset = 25; length = 7
>> substring = "John Do"
>> #1:
>> offset = 38; length = 8
>> substring = "John Foo"
>>
>> Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
>> ---
>>
>> Hi Michael,
>>
>> Now it's much better :)
>>
>> Cheers,
>>
>> Alex
>>
>>  man3/regex.3 | 42 +++++++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 42 insertions(+)
>>
>> diff --git a/man3/regex.3 b/man3/regex.3
>> index 7c5132995..72e576cc6 100644
>> --- a/man3/regex.3
>> +++ b/man3/regex.3
>> @@ -337,6 +337,48 @@ T}	Thread safety	MT-Safe
>>  .TE
>>  .SH CONFORMING TO
>>  POSIX.1-2001, POSIX.1-2008.
>> +.SH EXAMPLES
>> +.EX
>> +#include <stdint.h>
>> +#include <stdio.h>
>> +#include <stdlib.h>
>> +#include <regex.h>
>> +
>> +#define ARRAY_SIZE(arr) (sizeof((arr)) / sizeof((arr)[0]))
>> +
>> +static const char *const str =
>> +        "1) John Driverhacker;\en2) John Doe;\en3) John Foo;\en";
>> +static const char *const re = "John.*o";
>> +
>> +int main(void)
>> +{
>> +    static const char *s = str;
>> +    regex_t     regex;
>> +    regmatch_t  pmatch[1];
>> +    regoff_t    off, len;
>> +
>> +    if (regcomp(&regex, re, REG_NEWLINE))
>> +        exit(EXIT_FAILURE);
>> +
>> +    printf("String = \\"%s\\"\en", str);
> 
> 
> Here (twice)
> 
>> +    printf("Matches:\en");
>> +
>> +    for (int i = 0; ; i++) {
>> +        if (regexec(&regex, s, ARRAY_SIZE(pmatch), pmatch, 0))
>> +            break;
>> +
>> +        off = pmatch[0].rm_so + (s \- str);
>> +        len = pmatch[0].rm_eo \- pmatch[0].rm_so;
>> +        printf("#%d:\en", i);
>> +        printf("offset = %jd; length = %jd\en", (intmax_t) off, (intmax_t) len);
>> +        printf("substring = \\"%.*s\\"\en", len, s + pmatch[0].rm_so);
> 
> 
> And here (twice again)
> 
>> +
>> +        s += pmatch[0].rm_eo;
>> +    }
>> +
>> +    exit(EXIT_SUCCESS);
>> +}
>> +.EE
>>  .SH SEE ALSO
>>  .BR grep (1),
>>  .BR regex (7)
>>


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/