字符串函数 bcmp bcopy bzero memccpy memchr memcmp memcpy memicmp memmove memset movmem setmem stpcpy strcat strchr strcmp strcmpi strcpy strcspn strdup stricmp strlen strlwr strncat strncmp strncmpi strncpy strnicmp strpbrk strrev strset strstr strtok strupr	数学函数 abs acos asin atan atan2 ceil cos cosh exp fabs floor fmod frexp hypot ldexp log log10 modf pow pow10 sin sinh sqrt tan tanh 输入输出函数 getchar kbhit printf putchar	系统库函数 ClearScreen DispBCD SetScrollBar TextOut UpdateLCD bell block clrscr cursor delay get_chi_font get_eng_font getkey getpixel gotoxy line move noidle outtextxy putpixel pyfc rectangle sleep textmode time write_chi_font write_eng_font 标准函数 exit itoa	字符函数 isalnum isalpha iscntrl isdigit islower isascii isgraph isprint ispunct isspace isupper isxdigit toascii tolower toupper 动态内存分配函数 calloc free malloc realloc