lstrcmpiW function (winbase.h)

Article
01/26/2024

Compares two character strings. The comparison is not case-sensitive.

To perform a comparison that is case-sensitive, use the lstrcmp function.

Syntax

int lstrcmpiW(
  [in] LPCWSTR lpString1,
  [in] LPCWSTR lpString2
);

Parameters

[in] lpString1

Type: LPCWSTR

The first null-terminated string to be compared.

[in] lpString2

Type: LPCWSTR

The second null-terminated string to be compared.

Return value

Type: int

If the string pointed to by lpString1 is less than the string pointed to by lpString2, the return value is negative. If the string pointed to by lpString1 is greater than the string pointed to by lpString2, the return value is positive. If the strings are equal, the return value is zero.

Remarks

The lstrcmpi function compares two strings by checking the first characters against each other, the second characters against each other, and so on until it finds an inequality or reaches the ends of the strings.

Note that the lpString1 and lpString2 parameters must be null-terminated, otherwise the string comparison can be incorrect.

The function calls CompareStringEx, using the current thread locale, and subtracts 2 from the result, to maintain the C run-time conventions for comparing strings.

For some locales, the lstrcmpi function may be insufficient. If this occurs, use CompareStringEx to ensure proper comparison. For example, in Japan call with the NORM_IGNORECASE, NORM_IGNOREKANATYPE, and NORM_IGNOREWIDTH values to achieve the most appropriate non-exact string comparison. The NORM_IGNOREKANATYPE and NORM_IGNOREWIDTH values are ignored in non-Asian locales, so you can set these values for all locales and be guaranteed to have a culturally correct "insensitive" sorting regardless of the locale. Note that specifying these values slows performance, so use them only when necessary.

With a double-byte character set (DBCS) version of the system, this function can compare two DBCS strings.

The lstrcmpi function uses a word sort, rather than a string sort. A word sort treats hyphens and apostrophes differently than it treats other symbols that are not alphanumeric, in order to ensure that words such as "coop" and "co-op" stay together within a sorted list. For a detailed discussion of word sorts and string sorts, see Handling Sorting in Your Applications.

Security Remarks

See Security Considerations: International Features for security considerations regarding choice of comparison functions.

Note

The winbase.h header defines lstrcmpi as an alias that automatically selects the ANSI or Unicode version of this function based on the definition of the UNICODE preprocessor constant. Mixing usage of the encoding-neutral alias with code that is not encoding-neutral can lead to mismatches that result in compilation or runtime errors. For more information, see Conventions for Function Prototypes.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Target Platform	Windows
Header	winbase.h (include Windows.h)
Library	Kernel32.lib
DLL	Kernel32.dll

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