C++ Fundamentals for Professionals/

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Format

Format

Regular expressions can also specify the format of the target text. Find the implementation below.

We'll cover the following...

std::regex_replace and std::match_results.format, in combination with capture groups enable us to format text. We can use a format string together with a placeholder to insert the value.

Here are both possibilities:

C++
#include <regex>
 
#include <iomanip>
#include <iostream>
#include <string>
 
int main(){
 
  std::cout << std::endl;
 
  std::string future{"Future"};
  int len= sizeof(future);
 
  const std::string unofficial{"unofficial, C++0x"};
  const std::string official{"official, C++11"};
 
  std::regex regValues{"(.*), (.*)"};
 
 
  std::string standardText{"The $1 name of the new C++ standard is $2."};
 
  // using std::regex_replace
  std::string textNow= std::regex_replace(unofficial, regValues, standardText );
 
  std::cout <<  std::setw(len) << std::left << "Now: " << textNow << std::endl;
 
  // using std::match_results
  // typedef match_results<string::const_iterator> smatch;
  std::smatch smatch;
  if ( std::regex_match(official, smatch, regValues)){
 
    std::string textFuture= smatch.format(standardText);
    std::cout <<  std::setw(len) << std::left << "Future: " << textFuture << std::endl;
 
  }
 
  std::cout << std::endl;
}

In the function call std::regex_replace(unofficial, regValues, standardText) ...