icu::DateTimePatternGenerator Class Reference

This class provides flexible generation of date format patterns, like "yy-MM-dd". More...

`#include <dtptngen.h>`

Inheritance diagram for icu::DateTimePatternGenerator:

## Public Member Functions

virtual | ~DateTimePatternGenerator ()
| Destructor. More...
DateTimePatternGenerator * | clone () const
| Clone DateTimePatternGenerator object. More...
bool | operator== (const DateTimePatternGenerator &other) const
| Return true if another object is semantically equal to this one. More...
bool | operator!= (const DateTimePatternGenerator &other) const
| Return true if another object is semantically unequal to this one. More...
UnicodeString | getSkeleton (const UnicodeString &pattern, UErrorCode &status)
| Utility to return a unique skeleton from a given pattern. More...
UnicodeString | getBaseSkeleton (const UnicodeString &pattern, UErrorCode &status)
| Utility to return a unique base skeleton from a given pattern. More...
UDateTimePatternConflict | addPattern (const UnicodeString &pattern, UBool override, UnicodeString &conflictingPattern, UErrorCode &status)
| Adds a pattern to the generator. More...
void | setAppendItemFormat (UDateTimePatternField field, const UnicodeString &value)
| An AppendItem format is a pattern used to append a field if there is no good match. More...
const UnicodeString & | getAppendItemFormat (UDateTimePatternField field) const
| Getter corresponding to setAppendItemFormat. More...
void | setAppendItemName (UDateTimePatternField field, const UnicodeString &value)
| Sets the names of field, eg "era" in English for ERA. More...
const UnicodeString & | getAppendItemName (UDateTimePatternField field) const
| Getter corresponding to setAppendItemNames. More...
UnicodeString | getFieldDisplayName (UDateTimePatternField field, UDateTimePGDisplayWidth width) const
| The general interface to get a display name for a particular date/time field, in one of several possible display widths. More...
void | setDateTimeFormat (const UnicodeString &dateTimeFormat)
| The DateTimeFormat is a message format pattern used to compose date and time patterns. More...
const UnicodeString & | getDateTimeFormat () const
| Getter corresponding to setDateTimeFormat. More...
void | setDateTimeFormat (UDateFormatStyle style, const UnicodeString &dateTimeFormat, UErrorCode &status)
| dateTimeFormats are message patterns used to compose combinations of date and time patterns. More...
const UnicodeString & | getDateTimeFormat (UDateFormatStyle style, UErrorCode &status) const
| Getter corresponding to setDateTimeFormat. More...
UnicodeString | getBestPattern (const UnicodeString &skeleton, UErrorCode &status)
| Return the best pattern matching the input skeleton. More...
UnicodeString | getBestPattern (const UnicodeString &skeleton, UDateTimePatternMatchOptions options, UErrorCode &status)
| Return the best pattern matching the input skeleton. More...
UnicodeString | replaceFieldTypes (const UnicodeString &pattern, const UnicodeString &skeleton, UErrorCode &status)
| Adjusts the field types (width and subtype) of a pattern to match what is in a skeleton. More...
UnicodeString | replaceFieldTypes (const UnicodeString &pattern, const UnicodeString &skeleton, UDateTimePatternMatchOptions options, UErrorCode &status)
| Adjusts the field types (width and subtype) of a pattern to match what is in a skeleton. More...
StringEnumeration * | getSkeletons (UErrorCode &status) const
| Return a list of all the skeletons (in canonical form) from this class. More...
const UnicodeString & | getPatternForSkeleton (const UnicodeString &skeleton) const
| Get the pattern corresponding to a given skeleton. More...
StringEnumeration * | getBaseSkeletons (UErrorCode &status) const
| Return a list of all the base skeletons (in canonical form) from this class. More...
StringEnumeration * | getRedundants (UErrorCode &status)
| Return a list of redundant patterns are those which if removed, make no difference in the resulting getBestPattern values. More...
void | setDecimal (const UnicodeString &decimal)
| The decimal value is used in formatting fractions of seconds. More...
const UnicodeString & | getDecimal () const
| Getter corresponding to setDecimal. More...
UDateFormatHourCycle | getDefaultHourCycle (UErrorCode &status) const
| Get the default hour cycle for a locale. More...
virtual UClassID | getDynamicClassID () const override
| ICU "poor man's RTTI", returns a UClassID for the actual class. More...
Public Member Functions inherited from icu::UObject
virtual | ~UObject ()
| Destructor. More...

## Static Public Member Functions

static DateTimePatternGenerator * | createInstance (UErrorCode &status)
| Construct a flexible generator according to default locale. More...
static DateTimePatternGenerator * | createInstance (const Locale &uLocale, UErrorCode &status)
| Construct a flexible generator according to data for a given locale. More...
static DateTimePatternGenerator * | createInstanceNoStdPat (const Locale &uLocale, UErrorCode &status)
| For ICU use only. More...
static DateTimePatternGenerator * | createEmptyInstance (UErrorCode &status)
| Create an empty generator, to be constructed with addPattern(...) etc. More...
static UnicodeString | staticGetSkeleton (const UnicodeString &pattern, UErrorCode &status)
| Utility to return a unique skeleton from a given pattern. More...
static UnicodeString | staticGetBaseSkeleton (const UnicodeString &pattern, UErrorCode &status)
| Utility to return a unique base skeleton from a given pattern. More...
static UClassID | getStaticClassID (void)
| ICU "poor man's RTTI", returns a UClassID for this class. More...

## Detailed Description

This class provides flexible generation of date format patterns, like "yy-MM-dd".

The user can build up the generator by adding successive patterns. Once that is done, a query can be made using a "skeleton", which is a pattern which just includes the desired fields and lengths. The generator will return the "best fit" pattern corresponding to that skeleton.

The main method people will use is getBestPattern(String skeleton), since normally this class is pre-built with data from a particular locale. However, generators can be built directly from other data as well.

Issue: may be useful to also have a function that returns the list of fields in a pattern, in order, since we have that internally. That would be useful for getting the UI order of field elements.

Stable:
  ICU 3.8

Definition at line 58 of file dtptngen.h.

## Constructor & Destructor Documentation

## ~DateTimePatternGenerator()

virtual icu::DateTimePatternGenerator::~DateTimePatternGenerator | ( |  | ) |

virtual

Destructor.

Stable:
  ICU 3.8

## Member Function Documentation

## addPattern()

UDateTimePatternConflict icu::DateTimePatternGenerator::addPattern | ( | const UnicodeString & | pattern,
|  | UBool | override,
|  | UnicodeString & | conflictingPattern,
|  | UErrorCode & | status
| ) |  |

Adds a pattern to the generator.

If the pattern has the same skeleton as an existing pattern, and the override parameter is set, then the previous value is overridden. Otherwise, the previous value is retained. In either case, the conflicting status is set and previous vale is stored in conflicting pattern.

Note that single-field patterns (like "MMM") are automatically added, and don't need to be added explicitly!

Parameters

  pattern | Input pattern, such as "dd/MMM"
  override | When existing values are to be overridden use true, otherwise use false.
  conflictingPattern | Previous pattern with the same skeleton.
  status | Output param set to success/failure code on exit, which must not indicate a failure before the function call.

Returns
  conflicting status. The value could be UDATPG_NO_CONFLICT, UDATPG_BASE_CONFLICT or UDATPG_CONFLICT.

Stable:
  ICU 3.8

#### Sample code

#include <iostream>
#include "unicode/smpdtfmt.h"
#include "unicode/dtptngen.h"
#include "unicode/ustdio.h"
dtptngen.h
C++ API: Date/Time Pattern Generator.
smpdtfmt.h
C++ API: Format and parse dates in a language-independent manner.
ustdio.h
C API: Unicode stdio-like API.
UErrorCode status =U_ZERO_ERROR;
UnicodeString conflictingPattern,dateReturned, pattern;
Locale locale=Locale::getFrance();
Calendar *cal = Calendar::createInstance(status);
cal->set (1999,9,13,23,58,59);
UDate date = cal->getTime(status);
// Create an DateTimePatternGenerator instance for the given locale
DateTimePatternGenerator *dtfg= DateTimePatternGenerator::createInstance(locale,status);
SimpleDateFormat *sdf = new SimpleDateFormat(dtfg->getBestPattern("MMMMddHmm",status),locale,status);
// Add '. von' to the existing pattern
dtfg->addPattern("dd'. von' MMMM", true, conflictingPattern,status);
// Apply the new pattern
sdf->applyPattern(dtfg->getBestPattern("MMMMddHmm",status));
dateReturned = sdf->format(date, dateReturned, status);
pattern =sdf->toPattern(pattern);
u_printf("%s\n", "New Pattern for FRENCH: ");
u_printf("%S\n", pattern.getTerminatedBuffer());
u_printf("%s\n", "Date Time in new Pattern: ");
u_printf("%S\n", dateReturned.getTerminatedBuffer());
delete dtfg;
delete sdf;
delete cal;
icu::Calendar::createInstance
static Calendar * createInstance(UErrorCode &success)
Creates a Calendar using the default timezone and locale.
icu::DateTimePatternGenerator::createInstance
static DateTimePatternGenerator * createInstance(UErrorCode &status)
Construct a flexible generator according to default locale.
icu::Locale::getFrance
static const Locale & getFrance(void)
Useful constant for this country/region.
u_printf
U_CAPI int32_t u_printf(const char *patternSpecification,...)
Write formatted data to stdout.
UErrorCode
UErrorCode
Standard ICU4C error code type, a substitute for exceptions.
Definition: utypes.h:415
U_ZERO_ERROR
@ U_ZERO_ERROR
No error, no warning.
Definition: utypes.h:449
UDate
double UDate
Date and Time data type.
Definition: utypes.h:203

## clone()

DateTimePatternGenerator* icu::DateTimePatternGenerator::clone | ( |  | ) | const

Clone DateTimePatternGenerator object.

Clients are responsible for deleting the DateTimePatternGenerator object cloned.

Stable:
  ICU 3.8

## createEmptyInstance()

static DateTimePatternGenerator* icu::DateTimePatternGenerator::createEmptyInstance | ( | UErrorCode & | status | ) |

static

Create an empty generator, to be constructed with addPattern(...) etc.

Parameters

  status | Output param set to success/failure code on exit, which must not indicate a failure before the function call.

Stable:
  ICU 3.8

## createInstance() [1/2]

static DateTimePatternGenerator* icu::DateTimePatternGenerator::createInstance | ( | const Locale & | uLocale,
|  | UErrorCode & | status
| ) |  |

static

Construct a flexible generator according to data for a given locale.

Parameters

  uLocale |
  status | Output param set to success/failure code on exit, which must not indicate a failure before the function call.

Stable:
  ICU 3.8

## createInstance() [2/2]

static DateTimePatternGenerator* icu::DateTimePatternGenerator::createInstance | ( | UErrorCode & | status | ) |

static

Construct a flexible generator according to default locale.

Parameters

  status | Output param set to success/failure code on exit, which must not indicate a failure before the function call.

Stable:
  ICU 3.8

## createInstanceNoStdPat()

static DateTimePatternGenerator* icu::DateTimePatternGenerator::createInstanceNoStdPat | ( | const Locale & | uLocale,
|  | UErrorCode & | status
| ) |  |

static

For ICU use only.

Skips loading the standard date/time patterns (which is done via DateFormat).

Internal:
  Do not use. This API is for internal use only.

## getAppendItemFormat()

const UnicodeString& icu::DateTimePatternGenerator::getAppendItemFormat | ( | UDateTimePatternField | field | ) | const

Getter corresponding to setAppendItemFormat.

Values below 0 or at or above UDATPG_FIELD_COUNT are illegal arguments.

Parameters

  field | such as UDATPG_ERA_FIELD.

Returns
  append pattern for field

Stable:
  ICU 3.8

## getAppendItemName()

const UnicodeString& icu::DateTimePatternGenerator::getAppendItemName | ( | UDateTimePatternField | field | ) | const

Getter corresponding to setAppendItemNames.

Values below 0 or at or above UDATPG_FIELD_COUNT are illegal arguments. Note: The more general method for getting date/time field display names is getFieldDisplayName.

Parameters

  field | such as UDATPG_ERA_FIELD.

Returns
  name for field

See also
  getFieldDisplayName

Stable:
  ICU 3.8

## getBaseSkeleton()

UnicodeString icu::DateTimePatternGenerator::getBaseSkeleton | ( | const UnicodeString & | pattern,
|  | UErrorCode & | status
| ) |  |

Utility to return a unique base skeleton from a given pattern.

This is the same as the skeleton, except that differences in length are minimized so as to only preserve the difference between string and numeric form. So for example, both "MMM-dd" and "d/MMM" produce the skeleton "MMMd" (notice the single d). getBaseSkeleton() works exactly like staticGetBaseSkeleton(). Use staticGetBaseSkeleton() instead of getBaseSkeleton().

Parameters

  pattern | Input pattern, such as "dd/MMM"
  status | Output param set to success/failure code on exit, which must not indicate a failure before the function call.

Returns
  base skeleton, such as "MMMd"

Stable:
  ICU 3.8

## getBaseSkeletons()

StringEnumeration* icu::DateTimePatternGenerator::getBaseSkeletons | ( | UErrorCode & | status | ) | const

Return a list of all the base skeletons (in canonical form) from this class.

Parameters

  status | Output param set to success/failure code on exit, which must not indicate a failure before the function call.

Returns
  a StringEnumeration with the base skeletons. The caller must delete the object.

Stable:
  ICU 3.8

## getBestPattern() [1/2]

UnicodeString icu::DateTimePatternGenerator::getBestPattern | ( | const UnicodeString & | skeleton,
|  | UDateTimePatternMatchOptions | options,
|  | UErrorCode & | status
| ) |  |

Return the best pattern matching the input skeleton.

It is guaranteed to have all of the fields in the skeleton.

Parameters

  skeleton | The skeleton is a pattern containing only the variable fields. For example, "MMMdd" and "mmhh" are skeletons.
  options | Options for forcing the length of specified fields in the returned pattern to match those in the skeleton (when this would not happen otherwise). For default behavior, use UDATPG_MATCH_NO_OPTIONS.
  status | Output param set to success/failure code on exit, which must not indicate a failure before the function call.

Returns
  bestPattern The best pattern found from the given skeleton.

Stable:
  ICU 4.4

## getBestPattern() [2/2]

UnicodeString icu::DateTimePatternGenerator::getBestPattern | ( | const UnicodeString & | skeleton,
|  | UErrorCode & | status
| ) |  |

Return the best pattern matching the input skeleton.

It is guaranteed to have all of the fields in the skeleton.

Parameters

  skeleton | The skeleton is a pattern containing only the variable fields. For example, "MMMdd" and "mmhh" are skeletons.
  status | Output param set to success/failure code on exit, which must not indicate a failure before the function call.

Returns
  bestPattern The best pattern found from the given skeleton.

Stable:
  ICU 3.8

#### Sample code

#include <iostream>
#include "unicode/smpdtfmt.h"
#include "unicode/dtptngen.h"
#include "unicode/ustdio.h"
UnicodeString skeletons [] = {
UnicodeString("yQQQQ"), // year + full name of quarter, i.e., 4th quarter 1999
UnicodeString("yMMMM"), // year + full name of month, i.e., October 1999
UnicodeString("MMMMd"), // full name of month + day of the month, i.e., October 25
UnicodeString("hhmm"), // 12-hour-cycle format, i.e., 1:32 PM
UnicodeString("jjmm"), // preferred hour format for the given locale, i.e., 24-hour-cycle format for fr_FR
0,
};
Locale locales[] = {
Locale ("en_US"),
Locale ("fr_FR"),
Locale ("zh_CN"),
};
const char* filename = "sample.txt";
/* open a UTF-8 file for writing */
UFILE* f = u_fopen(filename, "w", nullptr,"UTF-8");
UnicodeString dateReturned;
UErrorCode status =U_ZERO_ERROR;
Calendar *cal = Calendar::createInstance(status);
cal->set (1999,9,13,23,58,59);
UDate date = cal->getTime(status);
u_fprintf(f, "%-20S%-20S%-20S%-20S\n", UnicodeString("Skeleton").getTerminatedBuffer(),UnicodeString("en_US").getTerminatedBuffer(),UnicodeString("fr_FR").getTerminatedBuffer(),UnicodeString("zh_CN").getTerminatedBuffer());
for (int i=0;!skeletons[i].isEmpty();i++) {
u_fprintf(f, "%-20S",skeletons[i].getTerminatedBuffer());
for (int j=0;j<sizeof(locales)/sizeof(locales[0]);j++) {
// create a DateTimePatternGenerator instance for given locale
DateTimePatternGenerator *dtfg= DateTimePatternGenerator::createInstance(locales[j],status);
// use getBestPattern method to get the best pattern for the given skeleton
UnicodeString pattern = dtfg->getBestPattern(skeletons[i],status);
// Constructs a SimpleDateFormat with the best pattern generated above and the given locale
SimpleDateFormat *sdf = new SimpleDateFormat(pattern,locales[j],status);
dateReturned.remove();
// Get the format of the given date
sdf->format(date,dateReturned,status);
/* write Unicode string to file */
u_fprintf(f, "%-20S", dateReturned.getTerminatedBuffer());
delete dtfg;
delete sdf;
}
u_fprintf(f,"\n");
}
/* close the file resource */
u_fclose(f);
delete cal;
u_fopen
U_CAPI UFILE * u_fopen(const char *filename, const char *perm, const char *locale, const char *codepage)
Open a UFILE.
u_fclose
U_CAPI void u_fclose(UFILE *file)
Close a UFILE.
u_fprintf
U_CAPI int32_t u_fprintf(UFILE *f, const char *patternSpecification,...)
Write formatted data to a UFILE.
UFILE
struct UFILE UFILE
Forward declaration of a Unicode-aware file.
Definition: ustdio.h:215

## getDateTimeFormat() [1/2]

const UnicodeString& icu::DateTimePatternGenerator::getDateTimeFormat | ( |  | ) | const

Getter corresponding to setDateTimeFormat.

There are four DateTimeFormats in a DateTimePatternGenerator object, corresponding to date styles UDAT_FULL..UDAT_SHORT. This method gets the style for UDAT_MEDIUM (the default). To get them individually, see getDateTimeFormat(UDateFormatStyle style).

Returns
  DateTimeFormat.

Stable:
  ICU 3.8

## getDateTimeFormat() [2/2]

const UnicodeString& icu::DateTimePatternGenerator::getDateTimeFormat | ( | UDateFormatStyle | style,
|  | UErrorCode & | status
| ) |  | const

Getter corresponding to setDateTimeFormat.

Parameters

  style | one of UDAT_FULL..UDAT_SHORT. Error if out of range.
  status | in/out parameter; if no failure status is already set, it will be set according to result of the function (e.g. U_ILLEGAL_ARGUMENT_ERROR for style out of range).

Returns
  the current dateTimeFormat for the the specified style, or empty string in case of error. The UnicodeString reference, or the contents of the string, may no longer be valid if setDateTimeFormat is called, or the DateTimePatternGenerator object is deleted.

Stable:
  ICU 71

## getDecimal()

const UnicodeString& icu::DateTimePatternGenerator::getDecimal | ( |  | ) | const

Getter corresponding to setDecimal.

Returns
  UnicodeString corresponding to the decimal point

Stable:
  ICU 3.8

## getDefaultHourCycle()

UDateFormatHourCycle icu::DateTimePatternGenerator::getDefaultHourCycle | ( | UErrorCode & | status | ) | const

Get the default hour cycle for a locale.

Uses the locale that the DateTimePatternGenerator was initially created with.

Cannot be used on an empty DateTimePatternGenerator instance.

Parameters

  status | Output param set to success/failure code on exit, which which must not indicate a failure before the function call. Set to U_UNSUPPORTED_ERROR if used on an empty instance.

Returns
  the default hour cycle.

Stable:
  ICU 67

## getDynamicClassID()

virtual UClassID icu::DateTimePatternGenerator::getDynamicClassID | ( |  | ) | const

overridevirtual

ICU "poor man's RTTI", returns a UClassID for the actual class.

Stable:
  ICU 3.8

Reimplemented from icu::UObject.

## getFieldDisplayName()

UnicodeString icu::DateTimePatternGenerator::getFieldDisplayName | ( | UDateTimePatternField | field,
|  | UDateTimePGDisplayWidth | width
| ) |  | const

The general interface to get a display name for a particular date/time field, in one of several possible display widths.

Parameters

  field | The desired UDateTimePatternField, such as UDATPG_ERA_FIELD.
  width | The desired UDateTimePGDisplayWidth, such as UDATPG_ABBREVIATED.

Returns
  The display name for field

Stable:
  ICU 61

## getPatternForSkeleton()

const UnicodeString& icu::DateTimePatternGenerator::getPatternForSkeleton | ( | const UnicodeString & | skeleton | ) | const

Get the pattern corresponding to a given skeleton.

Parameters

  skeleton |

Returns
  pattern corresponding to a given skeleton.

Stable:
  ICU 3.8

## getRedundants()

StringEnumeration* icu::DateTimePatternGenerator::getRedundants | ( | UErrorCode & | status | ) |

Return a list of redundant patterns are those which if removed, make no difference in the resulting getBestPattern values.

This method returns a list of them, to help check the consistency of the patterns used to build this generator.

Parameters

  status | Output param set to success/failure code on exit, which must not indicate a failure before the function call.

Returns
  a StringEnumeration with the redundant pattern. The caller must delete the object.

Internal:
  Do not use. This API is for internal use only. ICU 3.8

## getSkeleton()

UnicodeString icu::DateTimePatternGenerator::getSkeleton | ( | const UnicodeString & | pattern,
|  | UErrorCode & | status
| ) |  |

Utility to return a unique skeleton from a given pattern.

For example, both "MMM-dd" and "dd/MMM" produce the skeleton "MMMdd". getSkeleton() works exactly like staticGetSkeleton(). Use staticGetSkeleton() instead of getSkeleton().

Parameters

  pattern | Input pattern, such as "dd/MMM"
  status | Output param set to success/failure code on exit, which must not indicate a failure before the function call.

Returns
  skeleton such as "MMMdd"

Stable:
  ICU 3.8

## getSkeletons()

StringEnumeration* icu::DateTimePatternGenerator::getSkeletons | ( | UErrorCode & | status | ) | const

Return a list of all the skeletons (in canonical form) from this class.

Call getPatternForSkeleton() to get the corresponding pattern.

Parameters

  status | Output param set to success/failure code on exit, which must not indicate a failure before the function call.

Returns
  StringEnumeration with the skeletons. The caller must delete the object.

Stable:
  ICU 3.8

## getStaticClassID()

static UClassID icu::DateTimePatternGenerator::getStaticClassID | ( | void |  | ) |

static

ICU "poor man's RTTI", returns a UClassID for this class.

Stable:
  ICU 3.8

## operator!=()

bool icu::DateTimePatternGenerator::operator!= | ( | const DateTimePatternGenerator & | other | ) | const

Return true if another object is semantically unequal to this one.

Parameters

  other | the DateTimePatternGenerator object to be compared with.

Returns
  true if other is semantically unequal to this.

Stable:
  ICU 3.8

## operator==()

bool icu::DateTimePatternGenerator::operator== | ( | const DateTimePatternGenerator & | other | ) | const

Return true if another object is semantically equal to this one.

Parameters

  other | the DateTimePatternGenerator object to be compared with.

Returns
  true if other is semantically equal to this.

Stable:
  ICU 3.8

## replaceFieldTypes() [1/2]

UnicodeString icu::DateTimePatternGenerator::replaceFieldTypes | ( | const UnicodeString & | pattern,
|  | const UnicodeString & | skeleton,
|  | UDateTimePatternMatchOptions | options,
|  | UErrorCode & | status
| ) |  |

Adjusts the field types (width and subtype) of a pattern to match what is in a skeleton.

That is, if you supply a pattern like "d-M H:m", and a skeleton of "MMMMddhhmm", then the input pattern is adjusted to be "dd-MMMM hh:mm". This is used internally to get the best match for the input skeleton, but can also be used externally.

Parameters

  pattern | Input pattern
  skeleton | The skeleton is a pattern containing only the variable fields. For example, "MMMdd" and "mmhh" are skeletons.
  options | Options controlling whether the length of specified fields in the pattern are adjusted to match those in the skeleton (when this would not happen otherwise). For default behavior, use UDATPG_MATCH_NO_OPTIONS.
  status | Output param set to success/failure code on exit, which must not indicate a failure before the function call.

Returns
  pattern adjusted to match the skeleton fields widths and subtypes.

Stable:
  ICU 4.4

## replaceFieldTypes() [2/2]

UnicodeString icu::DateTimePatternGenerator::replaceFieldTypes | ( | const UnicodeString & | pattern,
|  | const UnicodeString & | skeleton,
|  | UErrorCode & | status
| ) |  |

Adjusts the field types (width and subtype) of a pattern to match what is in a skeleton.

That is, if you supply a pattern like "d-M H:m", and a skeleton of "MMMMddhhmm", then the input pattern is adjusted to be "dd-MMMM hh:mm". This is used internally to get the best match for the input skeleton, but can also be used externally.

Parameters

  pattern | Input pattern
  skeleton | The skeleton is a pattern containing only the variable fields. For example, "MMMdd" and "mmhh" are skeletons.
  status | Output param set to success/failure code on exit, which must not indicate a failure before the function call.

Returns
  pattern adjusted to match the skeleton fields widths and subtypes.

Stable:
  ICU 3.8

#### Sample code

#include <iostream>
#include "unicode/smpdtfmt.h"
#include "unicode/dtptngen.h"
#include "unicode/ustdio.h"
UFILE *out = u_finit(stdout, nullptr, "UTF-8");
UErrorCode status =U_ZERO_ERROR;
UnicodeString pattern,dateReturned;
Locale locale =Locale::getFrance();
Calendar *cal = Calendar::createInstance(status);
cal->set (1999,9,13,23,58,59);
UDate date = cal->getTime(status);
TimeZone *zone = TimeZone::createTimeZone(UnicodeString("Europe/Paris"));
DateTimePatternGenerator *dtfg = DateTimePatternGenerator::createInstance(locale,status);
SimpleDateFormat *sdf = new SimpleDateFormat("EEEE d MMMM y HH:mm:ss zzzz",locale,status);
sdf->setTimeZone(*zone);
pattern = sdf->toPattern(pattern);
u_fprintf(out, "%S\n", UnicodeString("Pattern before replacement:").getTerminatedBuffer());
u_fprintf(out, "%S\n", pattern.getTerminatedBuffer());
dateReturned.remove();
dateReturned = sdf->format(date, dateReturned, status);
u_fprintf(out, "%S\n", UnicodeString("Date/Time format in fr_FR:").getTerminatedBuffer());
u_fprintf(out, "%S\n", dateReturned.getTerminatedBuffer());
// Replace zone "zzzz" in the pattern with "vvvv"
UnicodeString newPattern = dtfg->replaceFieldTypes(pattern, "vvvv", status);
// Apply the new pattern
sdf->applyPattern(newPattern);
dateReturned.remove();
dateReturned = sdf->format(date, dateReturned, status);
u_fprintf(out, "%S\n", UnicodeString("Pattern after replacement:").getTerminatedBuffer());
u_fprintf(out, "%S\n", newPattern.getTerminatedBuffer());
u_fprintf(out, "%S\n", UnicodeString("Date/Time format in fr_FR:").getTerminatedBuffer());
u_fprintf(out, "%S\n", dateReturned.getTerminatedBuffer());
delete sdf;
delete dtfg;
delete zone;
delete cal;
u_fclose(out);
icu::TimeZone::createTimeZone
static TimeZone * createTimeZone(const UnicodeString &ID)
Creates a TimeZone for the given ID.
u_finit
U_CAPI UFILE * u_finit(FILE *f, const char *locale, const char *codepage)
Open a UFILE on top of an existing FILE* stream.

## setAppendItemFormat()

void icu::DateTimePatternGenerator::setAppendItemFormat | ( | UDateTimePatternField | field,
|  | const UnicodeString & | value
| ) |  |

An AppendItem format is a pattern used to append a field if there is no good match.

For example, suppose that the input skeleton is "GyyyyMMMd", and there is no matching pattern internally, but there is a pattern matching "yyyyMMMd", say "d-MM-yyyy". Then that pattern is used, plus the G. The way these two are conjoined is by using the AppendItemFormat for G (era). So if that value is, say "{0}, {1}" then the final resulting pattern is "d-MM-yyyy, G".

There are actually three available variables: {0} is the pattern so far, {1} is the element we are adding, and {2} is the name of the element.

This reflects the way that the CLDR data is organized.

Parameters

  field | such as UDATPG_ERA_FIELD.
  value | pattern, such as "{0}, {1}"

Stable:
  ICU 3.8

## setAppendItemName()

void icu::DateTimePatternGenerator::setAppendItemName | ( | UDateTimePatternField | field,
|  | const UnicodeString & | value
| ) |  |

Sets the names of field, eg "era" in English for ERA.

These are only used if the corresponding AppendItemFormat is used, and if it contains a {2} variable.

This reflects the way that the CLDR data is organized.

Parameters

  field | such as UDATPG_ERA_FIELD.
  value | name of the field

Stable:
  ICU 3.8

## setDateTimeFormat() [1/2]

void icu::DateTimePatternGenerator::setDateTimeFormat | ( | const UnicodeString & | dateTimeFormat | ) |

The DateTimeFormat is a message format pattern used to compose date and time patterns.

The default pattern in the root locale is "{1} {0}", where {1} will be replaced by the date pattern and {0} will be replaced by the time pattern; however, other locales may specify patterns such as "{1}, {0}" or "{1} 'at' {0}", etc.

This is used when the input skeleton contains both date and time fields, but there is not a close match among the added patterns. For example, suppose that this object was created by adding "dd-MMM" and "hh:mm", and its datetimeFormat is the default "{1} {0}". Then if the input skeleton is "MMMdhmm", there is not an exact match, so the input skeleton is broken up into two components "MMMd" and "hmm". There are close matches for those two skeletons, so the result is put together with this pattern, resulting in "d-MMM h:mm".

There are four DateTimeFormats in a DateTimePatternGenerator object, corresponding to date styles UDAT_FULL..UDAT_SHORT. This method sets all of them to the specified pattern. To set them individually, see setDateTimeFormat(UDateFormatStyle style, ...).

Parameters

  dateTimeFormat | message format pattern, here {1} will be replaced by the date pattern and {0} will be replaced by the time pattern.

Stable:
  ICU 3.8

## setDateTimeFormat() [2/2]

void icu::DateTimePatternGenerator::setDateTimeFormat | ( | UDateFormatStyle | style,
|  | const UnicodeString & | dateTimeFormat,
|  | UErrorCode & | status
| ) |  |

dateTimeFormats are message patterns used to compose combinations of date and time patterns.

There are four length styles, corresponding to the inferred style of the date pattern; these are UDateFormatStyle values:

- UDAT_FULL (for date pattern with weekday and long month), else
- UDAT_LONG (for a date pattern with long month), else
- UDAT_MEDIUM (for a date pattern with abbreviated month), else
- UDAT_SHORT (for any other date pattern). For details on dateTimeFormats, see https://www.unicode.org/reports/tr35/tr35-dates.html#dateTimeFormats. The default pattern in the root locale for all styles is "{1} {0}".

Parameters

  style | one of DateFormat.FULL..DateFormat.SHORT. Error if out of range.
  dateTimeFormat | the new dateTimeFormat to set for the the specified style
  status | in/out parameter; if no failure status is already set, it will be set according to result of the function (e.g. U_ILLEGAL_ARGUMENT_ERROR for style out of range).

Stable:
  ICU 71

## setDecimal()

void icu::DateTimePatternGenerator::setDecimal | ( | const UnicodeString & | decimal | ) |

The decimal value is used in formatting fractions of seconds.

If the skeleton contains fractional seconds, then this is used with the fractional seconds. For example, suppose that the input pattern is "hhmmssSSSS", and the best matching pattern internally is "H:mm:ss", and the decimal string is ",". Then the resulting pattern is modified to be "H:mm:ss,SSSS"

Parameters

  decimal |

Stable:
  ICU 3.8

## staticGetBaseSkeleton()

static UnicodeString icu::DateTimePatternGenerator::staticGetBaseSkeleton | ( | const UnicodeString & | pattern,
|  | UErrorCode & | status
| ) |  |

static

Utility to return a unique base skeleton from a given pattern.

This is the same as the skeleton, except that differences in length are minimized so as to only preserve the difference between string and numeric form. So for example, both "MMM-dd" and "d/MMM" produce the skeleton "MMMd" (notice the single d).

Parameters

  pattern | Input pattern, such as "dd/MMM"
  status | Output param set to success/failure code on exit, which must not indicate a failure before the function call.

Returns
  base skeleton, such as "MMMd"

Stable:
  ICU 56

## staticGetSkeleton()

static UnicodeString icu::DateTimePatternGenerator::staticGetSkeleton | ( | const UnicodeString & | pattern,
|  | UErrorCode & | status
| ) |  |

static

Utility to return a unique skeleton from a given pattern.

For example, both "MMM-dd" and "dd/MMM" produce the skeleton "MMMdd".

Parameters

  pattern | Input pattern, such as "dd/MMM"
  status | Output param set to success/failure code on exit, which must not indicate a failure before the function call.

Returns
  skeleton such as "MMMdd"

Stable:
  ICU 56

The documentation for this class was generated from the following file:

- i18n/unicode/dtptngen.h