linux下用C寫正則匹配IP和郵箱

一時想娛樂一下，寫了一段小程式，使用linux的正則庫匹配ip和email地址

#include <sys/types.h>#include <regex.h>#include <iostream>#include <string>#include <map>#include <algorithm>#include <cctype>using namespace std;string strtolower(string str);int main(int argc, const char *argv[]){    if (argc < 3) {        cout << "usage: regex <type> string" << endl;        return 0;    }    string type, str;    int result, z, reti;    regmatch_t pm[10];    const size_t nmatch = 10;    type = string((const char*)argv[1]);    str = string(argv[2]);    map<string, string> regs;    map<string, int> types;    regs["ip"] = "[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}";    regs["email"] = "[a-zA-Z0-9_.-]+@[a-zA-Z0-9_.-]+\\.[a-zA-Z0-9_.-]+";    types["ip"] = 1;    types["email"] = 2;    regex_t preg;    type = strtolower(type);    reti = regcomp(&preg, regs[type].c_str(), REG_EXTENDED|REG_NOSUB);    if (reti) {        char errbuf[1024];         regerror(reti, &preg, errbuf, 1024);        cout << "Could not compile regex with message "  << errbuf;exit(1);    }    result = regexec(&preg, str.c_str(), 0, NULL, 0);    switch (types[type]) {        case 1 :            if (result == REG_NOMATCH)                cout << "regcomp ip no match" << " reg express " + regs[type] << endl;            else if (!result) {  cout << "match" << endl;            }            break;    }    regfree(&preg);    return 0;}stringstrtolower(string str){    string tmp;    for(size_t i=0; i<str.length(); ++i)        tmp.push_back(tolower(str[i]));    return tmp;}