c++中CString:: Find , ReverseFind, Left, Right

In c++, CString is a class provided by MFC (Microsoft Foundation Class) that encapsulates a null-terminated string of characters. It is similar to the standard C string but provides additional functionality and ease of use.
1. Find: This method is used to find the first occurrence of a substring within the CString object. It takes the substring to search as a parameter and returns the zero-based index of the first occurrence if found, or -1 if not found. The method signature is:
```cpp
int Find(LPCTSTR lpszSub);
```
2. ReverseFind: This method is used to find the last occurrence of a substring within the CString object. It takes the substring to search as a parameter and returns the zero-based index of the last occurrence if found, or -1 if not found. The method signature is:
```cpp
int ReverseFind(LPCTSTR lpszSub);
```
3. Left: This method is used to extract a specified number of characters from the left side of the CString object. It takes the number of characters to extract as a parameter and returns a new CString object containing the extracted characters. The original CString object remains unchanged. The method signature is:
```cpp
CString Left(int nCount) const;
```
4. Right: This method is used to extract a specified number of characters from the right side of the CString object. It takes the number of characters to extract as a parameter and returns a new CString object containing the extracted characters. The original CString object remains unchanged. The method signature is:
```cpp
CString Right(int nCount) const;
```
These methods provide useful string manipulation functionality in C++ using the CString class.