bool IsChineseGBKChr(const char * szTerm){
if ((szTerm == NULL) || (strlen(szTerm) != 2)) return false;
unsigned char Chr[2];
Chr[0] = (unsigned char)szTerm[0];
Chr[1] = (unsigned char)szTerm[1];
return (((Chr[0] >= 0xB0) && (Chr[1] >= 0xA1) && (Chr[0] <= 0xF7) && (Chr[1]<= 0xFE)) ||
((Chr[0] >= 0x81) && (Chr[1] >= 0x40) && (Chr[0] <= 0xA0) && (Chr[1] <= 0xFE)) );
}
图解:

参考资料: