#include <sys/types.h>
#include <regex.h>

int main() {

   regex_t regtmp;

   if(regcomp (&regtmp,"(.+)upper\\1^", REG_EXTENDED|REG_ICASE | REG_NOSUB )==0)
        {               
                regmatch_t pmatch[1];
                regexec(&regtmp, "upperupperupperx",1, pmatch, 0);
                regfree(&regtmp);
        }

}