Source: Windows file Segmentation and merging

#include <Windows.h> #include <vector> #include <string>using namespace std;

Determine if the file exists bool Fileexistsw (const wstring &AMP;FN) {Win32_find_dataw fd;    HANDLE hfile = Findfirstfilew (Fn.c_str (), &AMP;FD);        if (hfile! = Invalid_handle_value) {:: FindClose (hfile);    return true; } return false;}    Determine if the directory exists bool DIRECTORYEXISTSW (const wstring &AMP;FN) {//Return Pathfileexistsa (Fn.c_str ());    DWORD Code = GETFILEATTRIBUTESW (Fn.c_str ()); Return (Code! = invalid_file_attributes) && ((File_attribute_directory & Code)! = 0);}    Directory + backslash wstring includetrailingpathdelimiterw (const wstring &path) {wstring s = path;    if (S.empty ()) return s;    if (S[s.length ()-1]! = L ' \ \ ') return s+l "\ \";  else return s;    }//gets the file name of the path wstring Extractfilenamew (const wstring &AMP;FILESTR) {if (Filestr.empty ()) return L ""; for (int i = Filestr.length ()-1; i>=0;-I.) {if (filestr[i] = = L ' \ \ ') {return filestr.subs        TR (i+1); }} return L "";} Std::wstring INTTOSTRW (constint i) {wchar_t buf[16]={0};    _itow_s (i,buf,10); Return wstring (BUF);} inline void incptr (void **p,int i) {*p = (void*) ((int) *p + i);} Split file bool Breakfile (const wchar_t *fn,unsigned long block_size,const wchar_t *save_path) {if (!    FILEEXISTSW (FN)) return false; if (!    DIRECTORYEXISTSW (Save_path)) return false;    if (Block_size < 1) return false;    HANDLE HF = Createfilew (fn,generic_read,file_share_read,null,open_existing,file_attribute_normal,0);        if (Invalid_handle_value = = HF) return false;    int iblock = 1;    Wstring Fblock = includetrailingpathdelimiterw (save_path) +extractfilenamew (FN) +l ". Part" +INTTOSTRW (Iblock); HANDLE HFW = Createfilew (Fblock.c_str (), generic_read|    generic_write,0,null,create_new,file_attribute_normal,0);        if (Invalid_handle_value = = HFW) {CloseHandle (HF);    return false;    } DWORD dwwrited = 0,dwwritedtemp = 0;    DWORD dwtowrite = 0;    DWORD dwremain = 0;    unsigned char buf[8192];DWORD dwreaded = 0;    int iseek = 0;    void *p = NULL;        while (true) {dwreaded = 0;        if (FALSE = = ReadFile (hf,buf,sizeof (BUF), &dwreaded,null)) break;        if (0 = = dwreaded) break;        iseek = 0;        p = (void*) buf;            Dwremain = Dwreaded;label_rewrite:if (dwwrited >= block_size) {:: CloseHandle (HFW);            ++iblock;            Fblock = Includetrailingpathdelimiterw (save_path) + Extractfilenamew (FN) +l ". Part" +INTTOSTRW (Iblock); HFW = Createfilew (Fblock.c_str (), generic_read|            generic_write,0,null,create_new,file_attribute_normal,0);                if (Invalid_handle_value = = HFW) {CloseHandle (HF);            return false;        } dwwrited = 0;        } incptr (&p,iseek);        dwtowrite = min (dwremain,block_size-dwwrited);        dwwritedtemp = 0;     if (FALSE = = WriteFile (hfw,p,dwtowrite,&dwwritedtemp,null)) break;   dwwrited + = dwwritedtemp;        if (Dwremain > dwwritedtemp) dwremain = dwremain-dwwritedtemp;        else Dwremain = 0;        iseek = dwwritedtemp;        if (Dwremain > 0) goto label_rewrite;    dwreaded = 0;    }:: CloseHandle (HFW);    :: CloseHandle (HF); return true;} Merge file bool Combinefiles (const vector<wstring> &files,const wstring &destfile) {if (FILEEXISTSW (destfile    )) return false;    if (Files.empty ()) return false; HANDLE HF = Createfilew (Destfile.c_str (), generic_read|    generic_write,0,null,create_new,file_attribute_normal,0);    if (Invalid_handle_value = = HF) return false;    HANDLE HFR = Invalid_handle_value;    unsigned char buf[8192];    DWORD dwreaded = 0,dwtowrite = 0,dwwrited = 0,dwremain = 0,dwwritedtemp = 0;    Longlong dwfilesize = 0,dwdestsize = 0;    Large_integer Li;    void *p=null;    int iseek = 0; for (size_t i = 0; I<files.size (); ++i) {if (! Fileexistsw (FILes[i]) continue;        HFR = Createfilew (Files[i].c_str (), generic_read,file_share_read,null,open_existing,file_attribute_normal,0);                if (Invalid_handle_value = = HFR) continue; Li.        QuadPart = 0;            if (FALSE = = GetFileSizeEx (Hfr,&li)) {CloseHandle (HF);        return false; } dwdestsize + = li.            QuadPart; } li.    QuadPart = dwdestsize;        if (FALSE = = SetFilePointerEx (hf,li,null,file_begin)) {CloseHandle (HF);    return false;        } if (FALSE = = SetEndOfFile (HF)) {CloseHandle (HF);    return false;    } CloseHandle (HF); HF = Createfilew (Destfile.c_str (), generic_read|    generic_write,0,null,open_existing,file_attribute_normal,0);        if (Invalid_handle_value = = HF) {HF = 0;    return false;    } HFR = Invalid_handle_value; for (size_t i = 0; I<files.size (); ++i) {if (!        FILEEXISTSW (Files[i]) continue; if (invalid_Handle_value! = HFR) CloseHandle (HFR);        HFR = Createfilew (Files[i].c_str (), generic_read,file_share_read,null,open_existing,file_attribute_normal,0);        if (Invalid_handle_value = = HFR) continue;label_read:dwreaded = 0;        if (FALSE = = ReadFile (hfr,buf,sizeof (BUF), &dwreaded,null)) continue;        if (dwreaded = = 0) continue;        iseek = 0;        p = (void*) buf;        Dwremain = Dwreaded;label_rewrite:incptr (&p,iseek);        Dwtowrite = Dwremain;        dwwritedtemp = 0;                if (FALSE = = WriteFile (hf,p,dwtowrite,&dwwritedtemp,null)) continue;        dwwrited + = dwwritedtemp;        if (Dwremain > dwwritedtemp) dwremain = Dwremain = Dwwritedtemp;        else Dwremain = 0;        iseek = dwwritedtemp;           if (dwremain>0) goto label_rewrite;    Goto Label_read;    } if (INVALID_HANDLE_VALUE!=HFR) CloseHandle (HFR); ClosehanDLE (HF); return true;}