std::regex_constants::error_type - cppreference.com (original) (raw)

Defined in header
using error_type = /* implementation-defined */; (1) (since C++11)
constexpr error_type error_collate = /* unspecified */; constexpr error_type error_ctype = /* unspecified */; constexpr error_type error_escape = /* unspecified */; constexpr error_type error_backref = /* unspecified */; constexpr error_type error_brack = /* unspecified */; constexpr error_type error_paren = /* unspecified */; constexpr error_type error_brace = /* unspecified */; constexpr error_type error_badbrace = /* unspecified */; constexpr error_type error_range = /* unspecified */; constexpr error_type error_space = /* unspecified */; constexpr error_type error_badrepeat = /* unspecified */; constexpr error_type error_complexity = /* unspecified */; constexpr error_type error_stack = /* unspecified */; (2) (since C++11) (inline since C++17)
  1. The error_type is a type that describes errors that may occur during regular expression parsing.

[edit] Constants

Name Explanation
error_collate the expression contains an invalid collating element name
error_ctype the expression contains an invalid character class name
error_escape the expression contains an invalid escaped character or a trailing escape
error_backref the expression contains an invalid back reference
error_brack the expression contains mismatched square brackets ('[' and ']')
error_paren the expression contains mismatched parentheses ('(' and ')')
error_brace the expression contains mismatched curly braces ('{' and '}')
error_badbrace the expression contains an invalid range in a {} expression
error_range the expression contains an invalid character range (e.g. [b-a])
error_space there was not enough memory to convert the expression into a finite state machine
error_badrepeat '*', '?', '+' or '{' was not preceded by a valid regular expression
error_complexity the complexity of an attempted match exceeded a predefined level
error_stack there was not enough memory to perform a match

[edit] Example

Implements regular expressions checker:

#include #include #include #include #include #include   void regular_expression_checker(const std::string& text, const std::string& regex, const std::regex::flag_type flags) { std::cout << "Text: " << std::quoted(text) << '\n' << "Regex: " << std::quoted(regex) << '\n';   try { const std::regex re{regex, flags}; const bool matched = std::regex_match(text, re);   std::stringstream out; out << (matched ? "MATCH!\n" : "DOES NOT MATCH!\n");   std::smatch m; if (std::regex_search(text, m, re); !m.empty()) { out << "prefix = [" << m.prefix().str().data() << "]\n";   for (std::size_t i{}; i != m.size(); ++i) out << " m[" << i << "] = [" << m[i].str().data() << "]\n";   out << "suffix = [" << m.suffix().str().data() << "]\n"; } std::cout << out.str() << '\n'; } catch (std::regex_error& e) { std::cout << "Error: " << e.what() << ".\n\n"; } }   int main() { constexpr std::regex::flag_type your_flags = std::regex::flag_type{0} // Choose one of the supported grammars: | std::regex::ECMAScript // | std::regex::basic // | std::regex::extended // | std::regex::awk // | std::regex::grep // | std::regex::egrep // Choose any of the next options: // | std::regex::icase // | std::regex::nosubs // | std::regex::optimize // | std::regex::collate // | std::regex::multiline ;   const std::string your_text = "Hello regular expressions."; const std::string your_regex = R"(([a-zA-Z]+) ([a-z]+) ([a-z]+).)"; regular_expression_checker(your_text, your_regex, your_flags);   regular_expression_checker("Invalid!", R"(((.)(.))", your_flags); regular_expression_checker("Invalid!", R"([.)", your_flags); regular_expression_checker("Invalid!", R"([.]{})", your_flags); regular_expression_checker("Invalid!", R"([1-0])", your_flags); }

Possible output:

Text: "Hello regular expressions." Regex: "([a-zA-Z]+) ([a-z]+) ([a-z]+)\." MATCH! prefix = [] m[0] = [Hello regular expressions.] m[1] = [Hello] m[2] = [regular] m[3] = [expressions] suffix = []   Text: "Invalid!" Regex: "((.)(.)" Error: Mismatched '(' and ')' in regular expression.   Text: "Invalid!" Regex: "[." Error: Unexpected character within '[...]' in regular expression.   Text: "Invalid!" Regex: "[.]{}" Error: Invalid range in '{}' in regular expression.   Text: "Invalid!" Regex: "[1-0]" Error: Invalid range in bracket expression..

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR Applied to Behavior as published Correct behavior
LWG 2053 C++11 the constants were declared static removed the static specifier

[edit] See also

| | reports errors generated by the regular expressions library (class) [edit] | | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |