regex_replace Function
Replaces matched regular expressions.
template<class OutIt, class BidIt, class RXtraits, class Alloc, class Elem>
OutIt regex_replace(OutIt out,
BidIt first, BidIt last,
const basic_regex<Elem, RXtraits, Alloc>& re,
const basic_string<Elem>& fmt,
match_flag_type flags = match_default);
template<class RXtraits, class Alloc, class Elem>
basic_string<Elem> regex_replace(const basic_string<Elem>& str,
const basic_regex<Elem, RXtraits, Alloc>& re,
const basic_string<Elem>& fmt,
match_flag_type flags = match_default);
The first function constructs a regex_iterator Class object iter(first, last, re, flags) and uses it to split its input range [first, last) into a series of subsequences T0M0T1M1...TN-1MN-1TN, where Mn is the nth match detected by the iterator. If no matches are found, T0 is the entire input range and N is zero. If (flags & format_first_only) != 0 only the first match is used, T1 is all of the input text that follows the match, and N is 1. For each i in the range [0, N), if (flags & format_no_copy) == 0 it copies the text in the range Ti to the iterator out. It then calls m.format(out, fmt, flags), where m is the match_results object returned by the iterator object iter for the subsequence Mi. Finally, if (flags & format_no_copy) == 0 it copies the text in the range TN to the iterator out. The function returns out.
The second function constructs a local variable result of type basic_string<charT> and calls regex_replace(back_inserter(result), str.begin(), str.end(), re, fmt, flags). It returns result.
// std_tr1__regex__regex_replace.cpp
// compile with: /EHsc
#include <regex>
#include <iostream>
int main()
{
char buf[20];
const char *first = "axayaz";
const char *last = first + strlen(first);
std::regex rx("a");
std::string fmt("A");
std::regex_constants::match_flag_type fonly =
std::regex_constants::format_first_only;
*std::regex_replace(&buf[0], first, last, rx, fmt) = '\0';
std::cout << "replacement == " << &buf[0] << std::endl;
*std::regex_replace(&buf[0], first, last, rx, fmt, fonly) = '\0';
std::cout << "replacement == " << &buf[0] << std::endl;
std::string str("adaeaf");
std::cout << "replacement == "
<< std::regex_replace(str, rx, fmt) << std::endl;
std::cout << "replacement == "
<< std::regex_replace(str, rx, fmt, fonly) << std::endl;
return (0);
}
replacement == AxAyAz replacement == Axayaz replacement == AdAeAf replacement == Adaeaf
