DATE-Format Functions

The ESQL/C DATE-format functions are as follows:

• rdatestr( )
• rstrdate( )
• rdefmtdate( )
• rfmtdate( )

These functions support extensions to format era-based DATE values:

• Support for the GL_DATE environment variable
• Era-based date formats of the DBDATE environment variable
• Extensions to the date-format strings for ESQL/C DATE-format functions
• Support for a precedence of date end-user formats

This section describes locale-specific behavior of the ESQL/C DATE-format functions. For details, see the IBM Informix: ESQL/C Programmer's Manual.

GL_DATE Support

The GL_DATE setting les can affect the results that these ESQL/C DATE-format functions generate. The end-user format that GL_DATE specifies overrides date end-user formats that the client locale defines. For more information, see Precedence for Date End-User Formats.

DBDATE Extensions

The ESQL/C DATE-format functions that support the extended era-based date syntax for the DBDATE environment variable are as follows:

• rdatestr( )
• rstrdate( )

When you set DBDATE to one of the era-based formats, these functions use era-based dates to convert between date strings and internal DATE values. The following ESQL/C example shows a call to the rdatestr() library function:

char str[100];
long jdate;
...
rdatestr(jdate, str);
printf("%s\n", str);

If you set DBDATE to GY2MD/ and CLIENT_LOCALE to the Japanese SJIS locale (ja_jp.sjis), the preceding code prints this value for the date 08/18/1990:

H02/08/18

If you set DBDATE to a era-based date format (which is specific to a Chinese or Japanese locale), make sure to set the CLIENT_LOCALE environment variable to a locale that supports era-based dates.

Extended DATE-Format Strings

The ESQL/C DATE-format functions that support the extended-DATE format strings are as follows:

• rdefmtdate( )
• rfmtdate( )

The following table shows the extended-format strings that these ESQL/C functions support for use with GLS locales. These extended-format strings format eras with 2-digit year offsets.

The following table shows some extended-format strings for era-based dates. These examples assume that the client locale is Japanese SJIS (ja_jp.sjis).

The following ESQL/C code fragment contains a call to the rdefmtdate() library function:

char fmt_str[100];
char in_str[100];
long jdate;
...
rdatestr("10/05/95", &jdate);
stcopy("gyy/mm/dd", fmt_str);
rdefmtdate(&jdate, fmt_str, in_str);
printf("Abbreviated Era Year: %s\n", in_str);

stcopy("eyymmdd", fmt_str);
rdefmtdate(&jdate, fmt_str, in_str);
printf("Full Era Year: %s\n", in_str);

When the CLIENT_LOCALE specifies the Japanese SJIS (ja_jp.sjis) locale, the code fragment displays the following output:

Abbreviated Era Year: H07/10/05
Full Era Year: H021005

Precedence for Date End-User Formats

The ESQL/C DATE-format functions use the following precedence to determine the end-user format for values in DATE columns:

1. The end-user format that DBDATE specifies (if DBDATE is set)
2. The end-user format that GL_DATE specifies (if GL_DATE is set)
3. The end-user date format that the client locale specifies (if CLIENT_LOCALE is set)
4. The end-user date format from the default locale: %m %d %iY

For more information on the precedence of DBDATE, GL_DATE, and CLIENT_LOCALE, refer to Date and Time Precedence.