This function compares two character strings, using the locale specified by the given identifier as the basis for the comparison.
At a Glance
| Header file: | Winnls.h |
| Windows CE versions: | 1.0 and later |
Syntax
int CompareString(LCID Locale, DWORD dwCmpFlags,
LPCTSTR lpString1, int cchCount1, LPCTSTR lpString2, int cchCount2);
Parameters
Locale
[in] Specifies the locale used for the comparison. This parameter can be one of the following predefined locale identifiers:
| Value | Description |
| LOCALE_SYSTEM_DEFAULT | The system’s default locale. |
| LOCALE_USER_DEFAULT | The current user’s default locale. |
This parameter can also be a locale identifier created by the MAKELCID macro.
dwCmpFlags
[in] A set of flags that indicate how the function compares the two strings. By default, these flags are not set. This parameter can specify zero to get the default behavior, or it can be any combination of the following values:
| Value | Description |
| NORM_IGNORECASE | Ignore case. |
| NORM_IGNOREKANATYPE | Do not differentiate between Hiragana and Katakana characters. Corresponding Hiragana and Katakana characters compare as equal. |
| NORM_IGNORENONSPACE | Ignore nonspacing characters. |
| NORM_IGNORESYMBOLS | Ignore symbols. |
| NORM_IGNOREWIDTH | Do not differentiate between a single-byte character and the same character as a double-byte character. |
| SORT_STRINGSORT | Treat punctuation the same as symbols. |
lpString1
[in] Pointer to the first string to be compared.
cchCount1
[in] Specifies the size, in characters, of the string pointed to by the lpString1 parameter. If this parameter is –1, the string is assumed to be null terminated and the length is calculated automatically.
lpString2
[in] Pointer to the second string to be compared.
cchCount2
[in] Specifies the size, in characters, of the string pointed to by the lpString2 parameter. If this parameter is –1, the string is assumed to be null terminated and the length is calculated automatically.
Return Values
If the function succeeds, the return value is one of the following values:
| Value | Description |
| CSTR_LESS_THAN | The string pointed to by the lpString1 parameter is less in lexical value than the string pointed to by the lpString2 parameter. |
| CSTR_EQUAL | The string pointed to by lpString1 is equal in lexical value to the string pointed to by lpString2. |
| CSTR_GREATER_THAN | The string pointed to by lpString1 is greater in lexical value than the string pointed to by lpString2. |
Zero indicates failure. To get extended error information, call GetLastError. Possible values for GetLastError include the following:
Remarks
Notice that if the return value is CSTR_EQUAL, which is the value 2, the two strings are “equal” in the collation sense, though not necessarily identical.
To maintain the C run-time convention of comparing strings, the value 2 can be subtracted from a nonzero return value. The meaning of < 0, ==0 and > 0 is then consistent with the C run times.
If the two strings are of different lengths, they are compared up to the length of the shortest one. If they are equal to that point, then the return value will indicate that the longer string is greater. For more information about locale identifiers, see Locale Identifiers.
Strings are compared using what is called a “string sort” technique. In a string sort, the hyphen and apostrophe are treated just like any other nonalphanumeric symbols: they come before the alphanumeric symbols.
The following list of words is sorted using a string sort:
| bill’s | t-ant |
| billet | t-aria |
| bills | tanya |
| can’t | sue’s |
| cannot | sued |
| cant | sues |
| co-op | we’re |
| con | went |
| coop | were |
The LCMapString function defaults to using a word sort, but uses a string sort if their caller sets the SORT_STRINGSORT flag.
The CompareString function is optimized to run at the highest speed when dwCmpFlags is set to 0 or NORM_IGNORECASE, and cchCount1 and cchCount2 have the value –1.
See Also