std::chrono::parse(3) C++ Standard Libary std::chrono::parse(3) NAME std::chrono::parse - std::chrono::parse Synopsis Defined in header <chrono> template< class CharT, class Parsable > (1) (since C++20) /* unspecified */ parse( const CharT* fmt, Parsable& tp ); template< class CharT, class Traits, class Alloc, class Parsable > /* unspecified */ parse( const std::basic_string<CharT, Traits, (2) (since C++20) Alloc>& fmt, Parsable& tp ); template< class CharT, class Traits, class Alloc, class Parsable > /* unspecified */ parse( const CharT* fmt, Parsable& tp, (3) (since C++20) std::basic_string<CharT, Traits, Alloc>& abbrev ); template< class CharT, class Traits, class Alloc, class Parsable > /* unspecified */ parse( const std::basic_string<CharT, Traits, Alloc>& fmt, (4) (since C++20) Parsable& tp, std::basic_string<CharT, Traits, Alloc>& abbrev ); template< class CharT, class Parsable > /* unspecified */ parse( const CharT* fmt, Parsable& tp, (5) (since C++20) std::chrono::minutes& offset ); template< class CharT, class Traits, class Alloc, class Parsable > /* unspecified */ parse( const std::basic_string<CharT, Traits, Alloc>& fmt, (6) (since C++20) Parsable& tp, std::chrono::minutes& offset ); template< class CharT, class Traits, class Alloc, class Parsable > /* unspecified */ parse( const CharT* fmt, Parsable& tp, std::basic_string<CharT, Traits, Alloc>& (7) (since C++20) abbrev, std::chrono::minutes& offset ); template< class CharT, class Traits, class Alloc, class Parsable > /* unspecified */ parse( const std::basic_string<CharT, Traits, Alloc>& fmt, Parsable& tp, (8) (since C++20) std::basic_string<CharT, Traits, Alloc>& abbrev, std::chrono::minutes& offset ); Returns an object manip of unspecified type such that, given a std::basic_istream<CharT, Traits> object is, the expression is >> manip calls from_stream (unqualified, to enable argument-dependent lookup) as fol- lows: 1) from_stream(is, fmt, tp) 2) from_stream(is, fmt.c_str(), tp) 3) from_stream(is, fmt, tp, std::addressof(abbrev)) 4) from_stream(is, fmt.c_str(), tp, std::addressof(abbrev)) 5) from_stream(is, fmt, tp, static_cast<std::basic_string<CharT, Traits, Al- loc>*>(nullptr), &offset) 6) from_stream(is, fmt.c_str(), tp, static_cast<std::basic_string<CharT, Traits, Al- loc>*>(nullptr), &offset) 7) from_stream(is, fmt, tp, std::addressof(abbrev), &offset) 8) from_stream(is, fmt.c_str(), tp, std::addressof(abbrev), &offset). The expression is >> manip is an lvalue of type std::ba- sic_istream<CharT, Traits> with the value is. These overloads participate in overload resolution only if the corre- sponding from_stream expression is well-formed. Implementations are recommended to make it difficult to use potentially dangling references to the format string, e.g., by making return types non-mov- able and preventing operator>> from accepting lvalues of return types. Parameters fmt - a format string (see below) tp - object to hold the parse result abbrev - string to hold the time zone abbreviation or name corresponding to the %Z specifier offset - duration to represent the offset from UTC corresponding to the %z specifier Format string The format string consists of zero or more conversion specifiers and or- dinary characters. Each ordinary character, excluding whitespace characters and the terminating null character, matches one identical character from the in- put stream, or causes the function to fail if the next character on the stream does not compare equal. Each whitespace character matches zero or more whitespace characters in the input stream. Each unmodified conversion specifier begins with a % character followed by a character that determines the behavior of the specifier. Some conversion specifiers have a modified form in which an E or O modifier character is inserted after the % character. Some conversion specifiers have a modified form in which a width parameter given as a positive decimal integer (shown as N below) is in- serted after the % character. Each conversion specifier causes the matched characters to be interpreted as parts of date and time types according to the table be- low. A character sequence in the format string that begins with a % but does not match one of the conversion specifiers below is interpreted as ordinary char- acters. If from_stream fails to parse everything specified by the format string, or if insufficient information is parsed to specify a complete result, or if parsing discloses contradictory information, is.setstate(std::ios_base::failbit) is called. The following conversion specifiers are available: Conversion Explanation specifier %% Matches a literal % character. %n Matches one whitespace character. %t Matches zero or one whitespace character. Year Parses the century as a decimal number. The width N specifies the %C maximum number of characters to read. The default width is 2. Leading %NC zeroes are permitted but not required. %EC The modified command %EC interprets the locale's alternative representation of the century. Parses the last two decimal digits of the year. If the cen- tury is not otherwise specified (e.g. with %C), values in the range [69, 99] are %y presumed to refer to the years 1969 to 1999, and values in the range %Ny [00, 68] are presumed to refer to the years 2000 to 2068. The width N %Ey specifies the maximum number of characters to read. The de- fault width is %Oy 2. Leading zeroes are permitted but not required. The modified commands %Ey and %Oy interpret the locale's al- ternative representation. Parses the year as a decimal number. The width N specifies the maximum %Y number of characters to read. The default width is 4. Leading zeroes are %NY permitted but not required. %EY The modified command %EY interprets the locale's alternative representation. Month %b %B Parses the locale's full or abbreviated case-insensitive month name. %h Parses the month as a decimal number (January is 1). The width N %m specifies the maximum number of characters to read. The de- fault width is %Nm 2. Leading zeroes are permitted but not required. %Om The modified command %Om interprets the locale's alternative representation. Day %d Parses the day of month as a decimal number. The width N specifies the %Nd maximum number of characters to read. The default width is 2. Leading %Od zeroes are permitted but not required. %e %Ne The modified commands %Od and %Oe interpret the locale's al- ternative %Oe representation. Day of the week %a Parses the locale's full or abbreviated case-insensitive weekday name. %A %u Parses the ISO weekday as a decimal number (1-7), where Mon- day is 1. The %Nu width N specifies the maximum number of characters to read. The default width is 1. Leading zeroes are permitted but not required. Parses the weekday as a decimal number (0-6), where Sunday is 0. The %w width N specifies the maximum number of characters to read. The default %Nw width is 1. Leading zeroes are permitted but not required. %Ow The modified command %Ow interprets the locale's alternative representation. ISO 8601 week-based year In ISO 8601 weeks begin with Monday and the first week of the year must satisfy the following requirements: * Includes January 4 * Includes first Thursday of the year %g Parses the last two decimal digits of the ISO 8601 week-based year. The %Ng width N specifies the maximum number of characters to read. The default width is 2. Leading zeroes are permitted but not required. %G Parses the ISO 8601 week-based year as a decimal number. The width N %NG specifies the maximum number of characters to read. The de- fault width is 4. Leading zeroes are permitted but not required. %V Parses the ISO 8601 week of the year as a decimal number. The width N %NV specifies the maximum number of characters to read. The de- fault width is 2. Leading zeroes are permitted but not required. Week/day of the year %j Parses the day of the year as a decimal number (January 1 is 1). The %Nj width N specifies the maximum number of characters to read. The default width is 3. Leading zeroes are permitted but not required. Parses the week number of the year as a decimal number. The first Sunday of the year is the first day of week 01. Days of the same year prior to %U that are in week 00. The width N specifies the maximum number of %NU characters to read. The default width is 2. Leading zeroes are permitted %OU but not required. The modified command %OU interprets the locale's alternative representation. Parses the week number of the year as a decimal number. The first Monday of the year is the first day of week 01. Days of the same year prior to %W that are in week 00. The width N specifies the maximum number of %NW characters to read. The default width is 2. Leading zeroes are permitted %OW but not required. The modified command %OW interprets the locale's alternative representation. Date %D Equivalent to "%m/%d/%y". %F Equivalent to "%Y-%m-%d". If the width is specified, it is only applied %NF to the %Y. Parses the locale's date representation. %x %Ex The modified command %Ex interprets the locale's alternate date representation. Time of day Parses the hour (24-hour clock) as a decimal number. The width N %H specifies the maximum number of characters to read. The de- fault width is %NH 2. Leading zeroes are permitted but not required. %OH The modified command %OH interprets the locale's alternative representation. Parses the hour (12-hour clock) as a decimal number. The width N %I specifies the maximum number of characters to read. The de- fault width is %NI 2. Leading zeroes are permitted but not required. %OI The modified command %OI interprets the locale's alternative representation. Parses the minute as a decimal number. The width N specifies the maximum %M number of characters to read. The default width is 2. Leading zeroes are %NM permitted but not required. %OM The modified command %OM interprets the locale's alternative representation. Parses the second as a decimal number. The width N specifies the maximum %S number of characters to read. The default width is 2. Leading zeroes are %NS permitted but not required. %OS The modified command %OS interprets the locale's alternative representation. %p Parses the locale's equivalent of the AM/PM designations as- sociated with a 12-hour clock. %R Equivalent to "%H:%M". %T Equivalent to "%H:%M:%S". %r Parses the locale's 12-hour clock time. Parses the locale's time representation. %X %EX The modified command %EX interprets the locale's alternate time representation. Miscellaneous Parses the locale's date and time representation. %c %Ec The modified command %Ec interprets the locale's alternative date and time representation. Parses the offset from UTC in the format [+|-]hh[mm]. For ex- ample -0430 refers to 4 hours 30 minutes behind UTC and 04 refers to 4 hours ahead %z of UTC. %Ez %Oz The modified commands %Ez and %Oz parses the format [+|-]h[h][:mm] (i.e., requiring a : between the hours and minutes and making the leading zero for hour optional). Parses the time zone abbreviation or name, taken as the longest sequence %Z of characters that only contains the characters A through Z, a through z, 0 through 9, -, +, _, and /. Example This section is incomplete Reason: no example Defect reports The following behavior-changing defect reports were applied retroac- tively to previously published C++ standards. DR Applied to Behavior as published Cor- rect behavior LWG 3554 C++20 overloads for plain null-terminated character added type sequences were missing See also from_stream(std::chrono::sys_time) parses a sys_time from a stream ac- cording to (C++20) the provided format (function template) from_stream(std::chrono::utc_time) parses a utc_time from a stream ac- cording to (C++20) the provided format (function template) from_stream(std::chrono::tai_time) parses a tai_time from a stream ac- cording to (C++20) the provided format (function template) from_stream(std::chrono::gps_time) parses a gps_time from a stream ac- cording to (C++20) the provided format (function template) from_stream(std::chrono::file_time) parses a file_time from a stream according to (C++20) the provided format (function template) from_stream(std::chrono::local_time) parses a local_time from a stream according to (C++20) the provided format (function template) from_stream parses a year from a stream accord- ing to the (C++20) provided format (function template) from_stream parses a month from a stream ac- cording to the (C++20) provided format (function template) from_stream parses a day from a stream accord- ing to the (C++20) provided format (function template) from_stream parses a weekday from a stream ac- cording to the (C++20) provided format (function template) from_stream parses a month_day from a stream according to (C++20) the provided format (function template) from_stream parses a year_month from a stream according to (C++20) the provided format (function template) from_stream parses a year_month_day from a stream according (C++20) to the provided format (function template) get_time parses a date/time value of speci- fied format (C++11) (function template) Category: * Todo no example http://cppreference.com 2024.06.10 std::chrono::parse(3)
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