C++

Reference

<regex>

class
<regex>

std::regex_error

class regex_error : public runtime_error { /* ... */ };
Regex exception
Objects of this exception type are thrown by the elements of the regex library.

It inherits from the standard exception runtime_error, and has a special public member function, code, which returns a specific code of type regex_constants::error_type depending on the kind of error that threw it:

flagerror
error_collateThe expression contained an invalid collating element name.
error_ctypeThe expression contained an invalid character class name.
error_escapeThe expression contained an invalid escaped character, or a trailing escape.
error_backrefThe expression contained an invalid back reference.
error_brackThe expression contained mismatched brackets ([ and ]).
error_parenThe expression contained mismatched parentheses (( and )).
error_braceThe expression contained mismatched braces ({ and }).
error_badbraceThe expression contained an invalid range between braces ({ and }).
error_rangeThe expression contained an invalid character range.
error_spaceThere was insufficient memory to convert the expression into a finite state machine.
error_badrepeatThe expression contained a repeat specifier (one of *?+{) that was not preceded by a valid regular expression.
error_complexityThe complexity of an attempted match against a regular expression exceeded a pre-set level.
error_stackThere was insufficient memory to determine whether the regular expression could match the specified character sequence.

Member functions

explicit regex_error (regex_constants::error_type ecode);
Constructs a regex exception with error code ecode.
regex_constants::error_type code() const;
Returns the error code with which it was constructed.
regex_constants::error_type is an enumerated type designed to uniquely identify errors in the regex library (see regex_constants for more info).

Example

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// regex_error
#include <iostream>
#include <regex>

int main ()
{
  try {
     std::regex myregex ("*");
  } catch (std::regex_error& e) {
     if (e.code() == std::regex_constants::error_badrepeat)
       std::cerr << "Repeat was not preceded by a valid regular expression.\n";
     else std::cerr << "Some other regex exception happened.\n";
  }
  return 0;
}

Output (stderr):
Repeat was not preceded by a valid regular expression.


See also

regex_constants
regex constants (namespace)
exception
Standard exception class (class)
runtime_error
Runtime error exception (class)