#ifndef _NTRTL_H

/**
 * The RtlCompareUnicodeString routine compares two Unicode strings.
 * 
 * \param[in] String1 Pointer to the first string.
 * \param[in] String2 Pointer to the second string.
 * \param[in] CaseInSensitive If TRUE, case should be ignored when doing the comparison.
 * \return A signed value that gives the results of the comparison.
 * \sa https://learn.microsoft.com/en-us/windows-hardware/drivers/ddi/wdm/nf-wdm-rtlcompareunicodestring
 */
_Must_inspect_result_
NTSYSAPI
LONG
NTAPI
RtlCompareUnicodeString(
    _In_ PCUNICODE_STRING String1,
    _In_ PCUNICODE_STRING String2,
    _In_ BOOLEAN CaseInSensitive
    );

#endif
View code on GitHub

// wdm.h

NTSYSAPI LONG RtlCompareUnicodeString(
  [in] PCUNICODE_STRING String1,
  [in] PCUNICODE_STRING String2,
  [in] BOOLEAN          CaseInSensitive
);
View the official Windows Driver Kit DDI reference