用C++写了个Convert类，仅供新手学习

Convert.h

class Convert
{
public:

	Convert(){}

	~Convert(){};


	//是否小写
	static bool islower(int c);
	//是否大写
	static bool isupper(int c);
	//转换成小写
	static int tolower(int c);
	//转换成大写
	static int toupper(int c);
	//是否是十进制
	static bool isdecimal(int c);
	//是否是二进制
	static bool isbinary(int c);
	//是否是八进制
	static bool isoctal(int c);
	//是否是十六进制
	static bool ishex(int c);
	//计算字符串长度
	static int strlen(const char *str);
	//查找指定字符
	static char *strchr(char *str, int c);
	//查找指定字符，忽略大小写
	static char *strchri(char *str, int c);
	//查找指定字符串
	static char *strstr(char *str, const char *substr);
	//查找指定字符串，忽略大小写
	static char *strstri(char *str, const char *substr);
	//复制字符串到缓存区中
	static char *strcpy(char *str1, const char *str2);
	//复制指定大小的字符串到缓冲区中
	static char *strcpyn(char *str1, const char *str2, int num);
	//连接字符串
	static char *strcat(char *str1, const char *str2);
	//比较字符串
	static int strcmp(char *str1, char *str2);
	//比较字符串，比较指定字节
	static int strncmp(char *str1, char *str2, int num);
	//比较字符串，忽略大小写
	static int strcmpi(char *str1, char *str2);
	//比较字符串，比较指定字节，忽略大小写
	static int strncmpi(char *str1, char *str2, int num);
	//32位整形转化成字符串
	static int itoa(int num, char *str);
	//32位无符号整形转化成字符串
	static int uitoa(unsigned int num, char *str);
	//字符串转化成32位整形
	static int atoi(char *str);

	//64位整形转化成字符串
	static int i64toa(__int64 num, char *str);
	//64位无符号整形转化成字符串
	static int ui64toa(unsigned __int64 num, char *str);
	//字符串转化成64位整形
	static __int64 atoi64(char *str);
	
	//多字节转化成宽字符字符串
	static int mbstowcs(char* ansi, wchar_t * uni, int num);
	//宽字符转化成多字节字符串
	static int wcstombs(wchar_t *uni, char* ansi, int num);
};
class Convert
{
public:

	Convert()