This function checks whether a character is a lead byte. A lead byte is the first byte of a character in a double-byte character set (DBCS).
TRUE indicates that the character is a lead byte. FALSE indicates that either the character is not a lead byte or an error was generated. For extended error information, call GetLastError.
Lead bytes are unique to double-byte character sets. A lead byte introduces a double-byte character. Lead bytes occupy a specific range of byte values. The IsDBCSLeadByte function uses the ANSI code page to check lead-byte ranges. To specify a different code page, use the IsDBCSLeadByteEx function.