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Regular expressions: Difference between revisions
C
m (Moved to Text cat) |
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return message
end try
=={{header|C}}==
{{works with|POSIX}}
As far as I can see, POSIX defined function for regex matching, but nothing for substitution. So we must do all the hard work ''by hand''. The complex-appearing code could be turned into a function.
<c>#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <regex.h>
#include <string.h>
int main()
{
regex_t preg;
regmatch_t substmatch[1];
char *tp = "string$";
char *t1 = "this is a matching string";
char *t2 = "this is not a matching string!";
char *ss = "istyfied";
regcomp(&preg, "string$", REG_EXTENDED);
printf("'%s' %smatched with '%s'\n", t1,
(regexec(&preg, t1, 0, NULL, 0)==0) ? "" : "did not ", tp);
printf("'%s' %smatched with '%s'\n", t2,
(regexec(&preg, t2, 0, NULL, 0)==0) ? "" : "did not ", tp);
regfree(&preg);
/* change "a[a-z]+" into "istifyed"?*/
regcomp(&preg, "a[a-z]+", REG_EXTENDED);
if ( regexec(&preg, t1, 1, substmatch, 0) == 0 )
{
//fprintf(stderr, "%d, %d\n", substmatch[0].rm_so, substmatch[0].rm_eo);
char *ns = malloc(substmatch[0].rm_so + 1 + strlen(ss) +
(strlen(t1) - substmatch[0].rm_eo) + 2);
memcpy(ns, t1, substmatch[0].rm_so+1);
memcpy(&ns[substmatch[0].rm_so], ss, strlen(ss));
memcpy(&ns[substmatch[0].rm_so+strlen(ss)], &t1[substmatch[0].rm_eo],
strlen(&t1[substmatch[0].rm_eo]));
ns[ substmatch[0].rm_so + strlen(ss) +
strlen(&t1[substmatch[0].rm_eo]) ] = 0;
printf("mod string: '%s'\n", ns);
free(ns);
} else {
printf("the string '%s' is the same: no matching!\n", t1);
}
regfree(&preg);
}</c>
=={{header|C++}}==
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