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udat.h File Reference

Detailed Description

C API: DateFormat.

Date Format C API

Date Format C API consists of functions that convert dates and times from their internal representations to textual form and back again in a language-independent manner. Converting from the internal representation (milliseconds since midnight, January 1, 1970) to text is known as "formatting," and converting from text to millis is known as "parsing." We currently define only one concrete structure UDateFormat, which can handle pretty much all normal date formatting and parsing actions.

Date Format helps you to format and parse dates for any locale. Your code can be completely independent of the locale conventions for months, days of the week, or even the calendar format: lunar vs. solar.

To format a date for the current Locale with default time and date style, use one of the static factory methods:

  UErrorCode status = U_ZERO_ERROR;
  UChar *myString;
  int32_t myStrlen = 0;
  UDateFormat* dfmt = udat_open(UCAL_DEFAULT, UCAL_DEFAULT, NULL, "PST", &status);
  myStrlen = udat_format(dfmt, myDate, NULL, myStrlen, NULL, &status);
      myString=(UChar*)malloc(sizeof(UChar) * (myStrlen+1) );
      udat_format(dfmt, myDate, myString, myStrlen+1, NULL, &status);
If you are formatting multiple numbers, it is more efficient to get the format and use it multiple times so that the system doesn't have to fetch the information about the local language and country conventions multiple times.
  UErrorCode status = U_ZERO_ERROR;
  int32_t i, myStrlen = 0;
  UChar* myString;
  char buffer[1024];
  UDate myDateArr[] = { 0.0, 100000000.0, 2000000000.0 }; // test values
  UDateFormat* df = udat_open(UCAL_DEFAULT, UCAL_DEFAULT, NULL, "GMT", &status);
  for (i = 0; i < 3; i++) {
      myStrlen = udat_format(df, myDateArr[i], NULL, myStrlen, NULL, &status);
      if(status == U_BUFFER_OVERFLOW_ERROR){
          status = U_ZERO_ERROR;
          myString = (UChar*)malloc(sizeof(UChar) * (myStrlen+1) );
          udat_format(df, myDateArr[i], myString, myStrlen+1, NULL, &status);
          printf("%s\n", u_austrcpy(buffer, myString) );
To get specific fields of a date, you can use UFieldPosition to get specific fields.
  UErrorCode status = U_ZERO_ERROR;
  UFieldPosition pos;
  UChar *myString;
  int32_t myStrlen = 0;
  char buffer[1024];

  pos.field = 1;  // Same as the DateFormat::EField enum
  UDateFormat* dfmt = udat_open(UCAL_DEFAULT, UCAL_DEFAULT, NULL, "PST", &status);
  myStrlen = udat_format(dfmt, myDate, NULL, myStrlen, &pos, &status);
      myString=(UChar*)malloc(sizeof(UChar) * (myStrlen+1) );
      udat_format(dfmt, myDate, myString, myStrlen+1, &pos, &status);
  printf("date format: %s\n", u_austrcpy(buffer, myString));
  buffer[pos.endIndex] = 0;   // NULL terminate the string.
  printf("UFieldPosition position equals %s\n", &buffer[pos.beginIndex]);
To format a date for a different Locale, specify it in the call to udat_open()
        UDateFormat* df = udat_open(UDAT_SHORT, UDAT_SHORT, "fr_FR", "GMT", &status);
You can use a DateFormat API udat_parse() to parse.
  UErrorCode status = U_ZERO_ERROR;
  int32_t parsepos=0;
  UDate myDate = udat_parse(df, myString, u_strlen(myString), &parsepos, &status);
You can pass in different options for the arguments for date and time style to control the length of the result; from SHORT to MEDIUM to LONG to FULL. The exact result depends on the locale, but generally: see UDateFormatStyle for more details You can also set the time zone on the format if you wish.

You can also use forms of the parse and format methods with Parse Position and UFieldPosition to allow you to

Definition in file udat.h.

#include "unicode/utypes.h"
#include "unicode/ucal.h"
#include "unicode/unum.h"

Go to the source code of this file.


typedef void * UDateFormat
typedef enum UDateFormatStyle UDateFormatStyle
typedef struct UDateFormatSymbols UDateFormatSymbols
typedef enum UDateFormatSymbolType UDateFormatSymbolType


enum  UDateFormatStyle {
enum  UDateFormatSymbolType {


U_CAPI void U_EXPORT2 udat_applyPattern (UDateFormat *format, UBool localized, const UChar *pattern, int32_t patternLength)
U_CAPI UDateFormat *U_EXPORT2 udat_clone (const UDateFormat *fmt, UErrorCode *status)
U_CAPI void U_EXPORT2 udat_close (UDateFormat *format)
U_CAPI int32_t U_EXPORT2 udat_countAvailable (void)
U_CAPI int32_t U_EXPORT2 udat_countSymbols (const UDateFormat *fmt, UDateFormatSymbolType type)
U_CAPI int32_t U_EXPORT2 udat_format (const UDateFormat *format, UDate dateToFormat, UChar *result, int32_t resultLength, UFieldPosition *position, UErrorCode *status)
U_CAPI UDate U_EXPORT2 udat_get2DigitYearStart (const UDateFormat *fmt, UErrorCode *status)
U_CAPI const char *U_EXPORT2 udat_getAvailable (int32_t index)
U_CAPI const UCalendar *U_EXPORT2 udat_getCalendar (const UDateFormat *fmt)
U_CAPI const UNumberFormat
udat_getNumberFormat (const UDateFormat *fmt)
U_CAPI int32_t U_EXPORT2 udat_getSymbols (const UDateFormat *fmt, UDateFormatSymbolType type, int32_t index, UChar *result, int32_t resultLength, UErrorCode *status)
U_CAPI UBool U_EXPORT2 udat_isLenient (const UDateFormat *fmt)
U_CAPI UDateFormat *U_EXPORT2 udat_open (UDateFormatStyle timeStyle, UDateFormatStyle dateStyle, const char *locale, const UChar *tzID, int32_t tzIDLength, const UChar *pattern, int32_t patternLength, UErrorCode *status)
U_CAPI UDate U_EXPORT2 udat_parse (const UDateFormat *format, const UChar *text, int32_t textLength, int32_t *parsePos, UErrorCode *status)
U_CAPI void U_EXPORT2 udat_parseCalendar (const UDateFormat *format, UCalendar *calendar, const UChar *text, int32_t textLength, int32_t *parsePos, UErrorCode *status)
U_CAPI void U_EXPORT2 udat_set2DigitYearStart (UDateFormat *fmt, UDate d, UErrorCode *status)
U_CAPI void U_EXPORT2 udat_setCalendar (UDateFormat *fmt, const UCalendar *calendarToSet)
U_CAPI void U_EXPORT2 udat_setLenient (UDateFormat *fmt, UBool isLenient)
U_CAPI void U_EXPORT2 udat_setNumberFormat (UDateFormat *fmt, const UNumberFormat *numberFormatToSet)
U_CAPI void U_EXPORT2 udat_setSymbols (UDateFormat *format, UDateFormatSymbolType type, int32_t index, UChar *value, int32_t valueLength, UErrorCode *status)
U_CAPI int32_t U_EXPORT2 udat_toPattern (const UDateFormat *fmt, UBool localized, UChar *result, int32_t resultLength, UErrorCode *status)

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