How to get file's modifycation time? - page 2

[ttechnik]

gchrmt4:

See https://docs.mql4.com/basis/types/string

MQL4 uses the same mechanism as many other languages such as C and Javascript where you can put special characters in a string constant by prefacing them with \

For example, "Column1\tColumn2" means "Column1 <tab> Column2". Similarly, "Column1\nColumn2" means "Column1 <new-line> Column2"

Because the \ character has a special meaning, you cannot just use \ in a string constant to mean "backslash". You have to use \\

\\ gets replaced with \ in the same way that \t gets replaced with <tab> and \n gets replaced with <new-line>

Therefore, if you do the following:

...you should see the output "c:\windows\win.ini"

Oh, yes, undestand it.

string filename="c:\windows\win.ini"; is  "c:\windows\win.ini"

string filename="c:\windows\nwin.ini"; is  "c:\windows"

Soo, good work, it will not be until after the BS n or t.

[MOHAMMED SAFAR AL-OTAIBI]

Alain Verleyen:
See https://www.mql5.com/en/forum/149304

Alain Verleyen

[James Cater]

Seeing as someone has dragged up this old thread....

There is now an MQL4 method to get the file modification time

https://docs.mql4.com/files/filegetinteger

[Maxwell_Owusu]

hello gurus here please i am stuck in my project.

please i want to read and write to external files in mql4 

i came across this documentation https://www.mql5.com/en/articles/1540 but it didnt work for me 

firstly i downloaded the kernel32 winAPI and placed it in mt4 libraries file and implemented he documentation code 

but it didnt work.

please help

#define GENERIC_READ    0x80000000
#define GENERIC_WRITE   0x40000000
#define FILE_SHARE_READ         0x00000001
#define FILE_SHARE_WRITE        0x00000002

#define CREATE_NEW              1
#define CREATE_ALWAYS           2
#define OPEN_ALWAYS             4
#define OPEN_EXISTING           3
#define TRUNCATE_EXISTING       5

#define FILE_BEGIN              0
#define FILE_CURRENT            1
#define FILE_END                2

#define INVALID_HANDLE_VALUE    -1
#import "kernel32.dll"
 
   int CreateFileW(string Filename, int AccessMode, int ShareMode, int PassAsZero, int CreationMode, int FlagsAndAttributes, int AlsoPassAsZero);
   int ReadFile(int FileHandle, int BufferPtr, int BufferLength, int & BytesRead[], int PassAsZero);
   int WriteFile(int FileHandle, int BufferPtr, int BufferLength, int & BytesWritten[], int PassAsZero);
   int SetFilePointer(int FileHandle, int Distance, int PassAsZero, int FromPosition);
   int GetFileSize(int FileHandle, int PassAsZero);
   int CloseHandle(int FileHandle);

   bool DeleteFileA(string Filename);

  int MulDiv(string X, int N1,int N2);
   // Used for temporary conversion of an array into a block of memory, which
   // can then be passed as an integer to ReadFile
   int LocalAlloc(int Flags, int Bytes);
   int RtlMoveMemory(int DestPtr, double & Array[], int Length);
   int LocalFree(int lMem);

   // Used for converting the address of an array to an integer 
   int GlobalLock(double & Array[]);
   bool GlobalUnlock(int hMem);
#import

int OpenNewFileForWriting(string FileName, bool ShareForReading = false)
{
   int ShareMode = 0;
   if (ShareForReading) ShareMode = FILE_SHARE_READ;

return CreateFileW(FileName, GENERIC_WRITE /*GENERIC_READ*/, 3 /*SHARE READ|WRITE*/, 0, CREATE_ALWAYS, 0, 0);
  // return (CreateFileA(FileName, GENERIC_WRITE, ShareMode, 0, CREATE_ALWAYS, 0, 0));
}

bool IsValidFileHandle(int FileHandle)
{
   return (FileHandle != INVALID_HANDLE_VALUE);
}

void CloseFile(int FileHandle)
{
   CloseHandle(FileHandle);
}

bool WriteToFile(int FileHandle, string DataToWrite)
{
   // Receives the number of bytes written to the file. Note that MQL can only pass 
   // arrays as by-reference parameters to DLLs
  int BytesWritten[1] = {0};

   // Get the length of the string 
   int szData = StringLen(DataToWrite);
Print(szData);
Print(DataToWrite);
   // Do the write 
   WriteFile(FileHandle, MulDiv(DataToWrite,1,1), szData, BytesWritten, 0);
   
   Print("BytesWritten = " + BytesWritten[0]);
   // Return true if the number of bytes written matches the expected number 
   return (BytesWritten[0] == szData);   
}

int start()
{
   string strTestFilename = "C:\\test2.txt";


   Print("About to write some example data to " + strTestFilename + "...");

   // Write some CRLF-terminated lines to the test file 
   int fWrite = OpenNewFileForWriting(strTestFilename, true);
   if (!IsValidFileHandle(fWrite))
   {
      Print("Unable to open " + strTestFilename + " for writing");
   } else {
      if((WriteToFile(fWrite, "Test12345678"))==TRUE) {
      Print("write ok"); 
      } else { Print("write not ok");  }
    }
    }