Defines | |||
![]() | ![]() | #define | UCOL_PRIMARYMASK |
![]() | ![]() | #define | UCOL_SECONDARYMASK |
![]() | ![]() | #define | UCOL_TERTIARYMASK |
![]() | ![]() | #define | UCOL_NULLORDER |
Typedefs | |||
![]() | ![]() | typedef void* | UCollator |
![]() | ![]() | A collator. More... | |
![]() | ![]() | typedef enum UCollationResult | UCollationResult |
![]() | ![]() | typedef enum UNormalizationMode | UNormalizationMode |
![]() | ![]() | typedef enum UNormalizationOption | UNormalizationOption |
![]() | ![]() | typedef enum UCollationStrength | UCollationStrength |
Enumerations | |||
![]() | ![]() | enum | UCollationResult { UCOL_EQUAL, UCOL_GREATER, UCOL_LESS } |
![]() | ![]() | Possible values for a comparison result. More... | |
![]() | ![]() | enum | UNormalizationMode { UCOL_NO_NORMALIZATION, UCOL_DECOMP_CAN, UCOL_DECOMP_COMPAT, UCOL_DECOMP_CAN_COMP_COMPAT, UCOL_DECOMP_COMPAT_COMP_CAN, UCOL_DEFAULT_NORMALIZATION } |
![]() | ![]() | Possible collation normalization modes. More... | |
![]() | ![]() | enum | UNormalizationOption { UCOL_IGNORE_HANGUL } |
![]() | ![]() | Possible normalization options. More... | |
![]() | ![]() | enum | UCollationStrength { UCOL_PRIMARY, UCOL_SECONDARY, UCOL_TERTIARY, UCOL_IDENTICAL, UCOL_DEFAULT_STRENGTH } |
![]() | ![]() | Possible collation strengths. More... |
The C API for Collator performs locale-sensitive String
comparison. You use this class to build searching and sorting routines for natural language text.
Like other locale-sensitive classes, you can use the function ucol_open()
, to obtain the appropriate pointer to UCollator
object for a given locale. If you need to understand the details of a particular collation strategy or if you need to modify that strategy.
The following example shows how to compare two strings using the UCollator
for the default locale.
// Compare two strings in the default locale UErrorCode success = U_ZERO_ERROR; UCollator* myCollator = ucol_open(NULL, &success); UChar source[4], target[4]; u_uastrcpy(source, "abc"); u_uastrcpy(target, "ABC"); if( u_strcoll(myCollator, source, u_strlen(source), target, u_strlen(target)) == UCOL_LESS) { printf("abc is less than ABC\n"); }else{ printf("abc is greater than or equal to ABC\n"); }
You can set a Collator
's strength property to determine the level of difference considered significant in comparisons. Four strengths are provided: UCOL_PRIMARY
, UCOL_SECONDARY
, UCOL_TERTIARY
, and UCOL_IDENTICAL
. The exact assignment of strengths to language features is locale dependant. For example, in Czech, "e" and "f" are considered primary differences, while "e" and "\u00EA" are secondary differences, "e" and "E" are tertiary differences and "e" and "e" are identical. The following shows how both case and accents could be ignored for US English.
//Get the Collator for US English and set its strength to UCOL_PRIMARY UErrorCode success = U_ZERO_ERROR; UCollator* usCollator = ucol_open("en_US", &success); ucol_setStrength(usCollator, UCOL_PRIMARY); UChar source[4], target[4]; u_uastrcpy(source, "abc"); u_uastrcpy(target, "ABC"); if( u_strcoll(myCollator, source, u_strlen(source), target, u_strlen(target)) == UCOL_EQUAL) { printf("'abc' and 'ABC' strings are equivalent with strength UCOL_PRIMARY\n"); }
For comparing String
s exactly once, the u_strcoll
method provides the best performance. When sorting a list of String
s however, it is generally necessary to compare each String
multiple times. In this case, sortKey
s provide better performance. The ucol_getsortKey
method converts a String
to a series of bits that can be compared bitwise against other sortKey
s using memcmp()
Note: UCollator
s with different Locale, Collation Strength and Decomposition Mode settings will return different sort orders for the same set of strings. Locales have specific collation rules, and the way in which secondary and tertiary differences are taken into account, for example, will result in a different sorting order for same strings.
#define UCOL_PRIMARYMASK () |
#define UCOL_SECONDARYMASK () |
#define UCOL_TERTIARYMASK () |
#define UCOL_NULLORDER () |
typedef void* UCollator |
A collator.
For usage in C programs.
typedef enum UCollationResult UCollationResult |
typedef enum UNormalizationMode UNormalizationMode |
typedef enum UNormalizationOption UNormalizationOption |
typedef enum UCollationStrength UCollationStrength |
enum UCollationResult |
Possible values for a comparison result.
UCOL_EQUAL | string a == string b. |
UCOL_GREATER | string a > string b. |
UCOL_LESS | string a < string b. |
enum UNormalizationMode |
Possible collation normalization modes.
UCOL_NO_NORMALIZATION | No decomposition/composition. |
UCOL_DECOMP_CAN | Canonical decomposition. |
UCOL_DECOMP_COMPAT | Compatibility decomposition. |
UCOL_DECOMP_CAN_COMP_COMPAT | Canonical decomposition followed by canonical composition. |
UCOL_DECOMP_COMPAT_COMP_CAN | Compatibility decomposition followed by canonical composition. |
UCOL_DEFAULT_NORMALIZATION | Default normalization. |
enum UNormalizationOption |
enum UCollationStrength |
Possible collation strengths.
UCOL_PRIMARY | Primary collation strength. |
UCOL_SECONDARY | Secondary collation strength. |
UCOL_TERTIARY | Tertiary collation strength. |
UCOL_IDENTICAL | Identical collation strength. |
UCOL_DEFAULT_STRENGTH | Default collation strength. |