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regex doesn't recognize a pattern in a string

P: n/a
Hello!
I've got a little problem - I'm writing a program in C++, which should
compare a text input from keyboard with a regular expression and
return what parttern was recognized and where. The problem is the
program doesn't find a pattern even if it actually is in the string.
This is the code:

#include <regex.h>
#include <iostream>
#include <string>

using namespace std;

int main()
{
regex_t preg;
string s;
string pattern = "\\(Name is [a-zA-Z]+\\)"; // "\\1" na koncu
wyrazenia
oznaczałoby dopasowanie jeszcze raz tego, co znajdzie do wyrazenia w
nawiasach
int rc;
size_t nmatch = 2;
regmatch_t pmatch[2];

cout << "Podaj string, w ktorym bedzie wyszukany wzorzec\n";

getline(cin, s); //wczytuje do konca linii - w przeciwienstwie do
cin >>,
ktore wczytuje do spacji
cout << s << endl;

if(0 != (rc = regcomp(&preg, pattern.c_str(), REG_EXTENDED)))
{
printf("regcomp: Nie udalo sie skompilowac wyrazenia.");
exit(EXIT_FAILURE);
}

if(0 != (rc = regexec(&preg, s.c_str(), nmatch, pmatch, 0)) ) //
funkcja
c_str zamienia typ string na const char *
{
printf("regexec: Nie udalo sie dopasowac stringu %s do
wyrazenia %s, rc =
%d\n", s.c_str(), pattern.c_str(), rc);
}
else
{
printf("W całym wyrażeniu dopasowano wzorzec: \"%.*s\" na
pozycji od %d do
%d\n", pmatch[0].rm_eo-pmatch[0].rm_so, &s[pmatch[0].rm_so],
pmatch[0].rm_so, pmatch[0].rm_eo - 1);
}

regfree(&preg);

return 0;
}

Any suggestions?

Nov 7 '07 #1
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2 Replies


P: n/a
hogcia a écrit :
Hello!
I've got a little problem - I'm writing a program in C++, which should
compare a text input from keyboard with a regular expression and
return what parttern was recognized and where. The problem is the
program doesn't find a pattern even if it actually is in the string.
This is the code:
[snip]
regex_t preg;
string s;
string pattern = "\\(Name is [a-zA-Z]+\\)"; // "\\1" na koncu
[snip]

if(0 != (rc = regcomp(&preg, pattern.c_str(), REG_EXTENDED)))
[snip]

Any suggestions?
You are using EXTENDED regular expression so the ( is special by default.
your pattern should be:
string pattern = "(Name is [a-zA-Z]+)";

Michael
Nov 7 '07 #2

P: n/a
hogcia wrote:
Hello!
I've got a little problem - I'm writing a program in C++, which should
compare a text input from keyboard with a regular expression and
return what parttern was recognized and where. The problem is the
program doesn't find a pattern even if it actually is in the string.
This is the code:
OK, now give us the input you gave it, what you were expecting it to
say, and what you observed.
Nov 7 '07 #3

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