std::match_results::format

template< class OutputIt >
OutputIter format( OutputIt out,
                   const char_type* fmt_first, const char_type* fmt_last,
                   std::regex_constants::match_flag_type flags =
                       std::regex_constants::format_default ) const;

(1)

(since C++11)

template< class OutputIt, class ST, class SA >
OutputIter format( OutputIt out,
                   const basic_string<char_type,ST,SA>& fmt,
                   std::regex_constants::match_flag_type flags =
                       std::regex_constants::format_default ) const;

(2)

(since C++11)

template< class ST, class SA >
std::basic_string<char_type,ST,SA> 
    format( const std::basic_string<char_type,ST,SA>& fmt,
            std::regex_constants::match_flag_type flags =
                std::regex_constants::format_default ) const;

(3)

(since C++11)

string_type format( const char_type* fmt_s,
                    std::regex_constants::match_flag_type flags =
                        std::regex_constants::format_default ) const;

(4)

(since C++11)

format outputs a format string, replacing any format specifiers or escape sequences in that string with match data from *this.

1) The format character sequence is defined by the range [fmt_first, fmt_last). The resulting character sequence is copied to out.

2) The format character sequence is defined by the characters in fmt. The resulting character sequence is copied to out.

3-4) The format character sequence is defined by the characters in fmt and fmt_s respectively. The resulting character sequence is copied to a newly constructed std::basic_string, which is returned.

The flags bitmask determines which format specifiers and escape sequences are recognized.

The behavior of format is undefined if ready() != true.

Parameters

fmt_begin, fmt_end	-	pointers to a range of characters defining the format character sequence
fmt	-	`std::basic_string` defining the format character sequence
fmt_s	-	pointer to a null-terminated character string defining the format character sequence
out	-	iterator that the resulting character sequence is copied to
flags	-	`std::regex_constants::match_flag_type` bitmask specifying which format specifiers and escape sequences are recognized
Type requirements
- `OutputIt` must meet the requirements of `OutputIterator`.

Return value

1-2) out

3-4) The newly constructed string containing resulting character sequence.

Exceptions

(none).

Example

#include <iostream>
#include <string>
#include <regex>
  
int main()
{
    std::string s = "for a good time, call 867-5309";
    std::regex phone_regex("\\d{3}-\\d{4}");
    std::smatch phone_match;
  
    if (std::regex_search(s, phone_match, phone_regex)) {
        std::string fmt_s = phone_match.format(
            "$`"    // $` means characters before the match
            "[$&]"  // $& means the matched characters
            "$'");  // $' means characters following the match
        std::cout << fmt_s << '\n';
    }   
}

Output:

1	`for` `a good` `time, call [867-5309]`

regex_replace (C++11)	replaces occurrences of a regular expression with formatted replacement text (function template)
match_flag_type (C++11)	options specific to matching (typedef)

std::match_results::format

Parameters

Return value

Exceptions

Example

See also