string字符串操作封装

#pragma once
#include 
#include 
#include 


#ifdef _UNICODE
#define string_t std::wstring
#else
#define string_t std::string
#endif

#define CODE_CONVERT_USE_WIN32

class zzc_string
{
public:
	zzc_string() {}
	~zzc_string() {}

public:
	//裁剪：
	static std::string& trim_l(std::string &str);
	static std::string& trim_r(std::string &str);
	static std::string& trim(std::string &str);
	
	//大小写转换：
	static std::string& to_upper(std::string &str);
	static std::string to_upper_copy(std::string &str);
	static std::string& to_lower(std::string &str);
	static std::string to_lower_copy(std::string &str);

	//反转
	static std::string& reverse(std::string &str);
	static std::string reverse_copy(std::string &str);

	//截取
	static std::string left(std::string &str, size_t n_count);
	static std::string right(std::string &str, size_t n_count);
	static std::string mid(std::