Traverse folder under C + +

The program iterates through all the files in the folder and its subfolders and outputs them to the standard output stream or file stream.

1. Consider traversing all files in a single-level directory. Take C:\WINDOWS as an example:

A pointer to a data structure _finddata_t, a file information struct.

struct _finddata_t
{
    unsigned attrib;     File properties
    time_t time_create;  File creation time
    time_t time_access;  File last access time
    time_t Time_write;   Last modification time of the file
    _fsize_t size;  Number of File bytes
    Char Name[_max_fname]; Filename

The file attributes are unsigned integers, and the values are the corresponding macros: _a_arch (archive), _a_subdir (folder), _a_hidden (hidden), _a_system (System), _a_normal (normal), _a_rdonly (read-only). It is easy to see that through this structure, we can get a lot of information about the file. By combining the following functions, we can store the file information in this struct:

Match the first file of the current directory by the filename naming rule

Match the current directory to the next file by the filename naming rule
_findnext (_in_ intptr_t _findhandle, _out_ struct _finddata64i32_t * _finddata);
Closes the file handle returned by _findfirst
_findclose (_in_ intptr_t _findhandle);

The _findfirst function returns a handle to the file, with a data type of long. The traversal process can specify the file type, which is implemented by the assignment of the filename, for example, to traverse all the. exe files under C:\WINDOWS

BOOL Transfer (String fileName = "C:\\windows\\*.exe", int exenum = 0)
{
_finddata_t FileInfo;
Long handle = _findfirst (Filename.c_str (), &fileinfo);

if (handle = = -1l)
{
Cerr << "Failed to transfer files" << Endl;
return false;
}

Do
{
Exenum + +;
cout << Fileinfo.name <<endl;
} while (_findnext (handle, &fileinfo) = = 0);
cout << ". exe files ' number:" << exenum << Endl;

return true;
}

BOOL Transfer (String fileName = "C:\\windows\\*.exe", int exenum = 0)
{
    _finddata_t FileInfo;
    Long handle = _findfirst (Filename.c_str (), &fileinfo);

    if (handle = = -1l)
    {
        Cerr << "Failed to transfer files" << Endl;
        return false;
    }

    
    {
        Exenum + +;
        cout << Fileinfo.name <<endl;
    } while (_findnext (handle, &fileinfo) = = 0);
    cout << ". exe files ' number:  " << exenum << Endl;

    return true;
}

2. Traverse all files under the folder and its subfolders. The folder directory in the operating system is a tree structure that uses a deep search strategy to traverse all files. Using the _a_subdir property, you can run the following program:

void Dfsfolder (String folderpath, Ofstream &fout)
{
_finddata_t FileInfo;
string strfind = FolderPath + "\\*";
Long Handle = _findfirst (Strfind.c_str (), &fileinfo);

if (Handle = = -1l)
{
cerr << "can not match the folder path" << Endl;
exit ( -1);
}
do{
//Determine if there is a subdirectory
if (Fileinfo.attrib & _a_subdir)
{
//This statement is important
if (strcmp (Fileinfo.name, ".")! = 0) && (strcmp (Fileinfo.name, "...")! = 0))
{
string NewPath = FolderPath + "\ \" + Fileinfo.name;
Dfsfolder (NewPath, fout);
}
}
Else
{
fout << folderpath << "\ \" << fileinfo.name << "";
}
}while (_findnext (Handle, &fileinfo) = = 0);

_findclose (Handle);
Fout.close ();
}

 void Dfsfolder (String folderpath, Ofstream &fout) 
 {
 _finddata_t FileInfo; 
 String strfind = FolderPath + "\\*"; 
 Long Handle = _findfirst (Strfind.c_str (), &fileinfo);        
 
 if (Handle = = -1l) 
 {
 Cerr << "can not match the folder path" << Endl; 
 Exit (-1);            
} 
 do{
//Determine if there are subdirectories 
 if (Fileinfo.attrib & _a_subdir) 
 {
 This statement is important 
 if (strcmp (Fileinfo.name, ".")! = 0) && (strcmp (Fileinfo.name, "...")!                = 0)) 
 {
 String newpath = FolderPath + "\ \" + Fileinfo.name; 
 Dfsfolder (NewPath, fout); 
} 
} 
 Else 
 {
 Fout << folderpath << "\ \" <&L T Fileinfo.name << ""; 
} 
}while (_findnext (Handle, &fileinfo) = = 0);    
 
 _findclose (Handle); 
 Fout.close (); 
} 

In the If branch where there is no subdirectory, as the system enters a subdirectory, the first two files (clips) that match are "." (current directory), "..." (Previous level directory). You need to ignore both of these situations. When you need to process a traversed file, add the appropriate code to the Else branch.

Traverse folder under C + +