Pointer to Array of Strings Is Fine in Function but not outside

Question

I'm working with PCRE library for C on a linux x86_64 system, though I don't think the PCRE is to blame for the issue I'm having. Basically I have an array of character arrays that holds the result from the PCRE check. I used typedef to keep it clean

typedef char *pcreres[30];

And the function that handles checking for matches, etc

int getmatch(const char *pattern, char *source, pcreres *res){
const char *error;
    int erroffset, rc,i;
    int ovector[30];

    pcre *re = pcre_compile(pattern,PCRE_CASELESS | PCRE_MULTILINE, &error,&erroffset,NULL);
    rc=pcre_exec(re,NULL,source,(int)strlen(source),0,0,ovector,30);

    if(rc<0){
        return -1;
    }
    if(rc==0) rc=10;
    for(i=0;i<rc;i++){
        char *substring_start=source+ovector[2*i];
        int substring_length=ovector[2*i+1] - ovector[2*i];
        *res[i] = strndup(substring_start,substring_length);
    }
    return rc;
}

The code I'm testing has 2 results and if I put a printf("%s",*res[1]) in the function just before the return I get the expected result.

However in my main function where I call getmatch() from I have this code;

pcreres to;
mres=getmatch(PATTERN_TO,email,&to);
printf("%s",to[1]);

I get an empty string, however to[0] outputs the correct result.

I'm somewhat a newbie at C coding, but I'm completely lost at where to go from here.

Any help is appreciated!

Dave Rager · Accepted Answer · 2011-09-30 18:04:25Z

3

Operator precedence. the [] operator is evaluated before the * operator. In your function try this:

(*res)[i] = strndup(substring_start,substring_length);

answered Sep 30, 2011 at 18:04

Dave Rager

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1 Comment

Andy Meyers Over a year ago

That was it! I'm sure I won't forget this in the future. Thank you for your help!

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