Save data to text file in C++

[nsw1216]

Hello?
I am new in Visual C++ programming and interfacing. Currently I am trying to create an monitoring system interface which can communicate with my PIC USB device. I have created an interface which can read and send information from/to PIC.

Now, I would like to add a function which is saving data of my monitoring system from time to time as a record in text. However, i only found the manually saving data examples but not the automatically type.

Is there anyone know what should I do to achieve what i want ?
Is there any examples about this matter ?

Your help are most welcome and appreciated.
By the way, I am using Microsoft Visual Studio 2010 in this project.

Thank you.

 

[horace1]

when you receive your data from the USB device you can use the standard C++ file IO methods
Input/Output with files - C++ Documentation

 

[nsw1216]

horace1,

But i noticed that, from the example i found, the syntax used in the examples are different for the standard C++ file IO methods.
For example,

private: System::Void SaveData_Click(System::Object^  sender, System::EventArgs^  e) {
		 if(AttachedState == TRUE)
		 {
			double TTemperature = TemperatureValue/2.0;
			double TTemperature1 = TemperatureValue1/2.0;
			String^ fileName = "MonitoringData-%date:~4,2%-%date:~7,2%-%date:~12,2%.txt";
			StreamWriter^ sw = gcnew StreamWriter(fileName);
			sw->WriteLine("Data Logged at {0}",DateTime::Now);
			sw->WriteLine("");
			sw->WriteLine("Temperature   : {0} Degree Celsius", TTemperature);
			sw->WriteLine("Temperature1   : {0} Degree Celsius", TTemperature1);
			sw->WriteLine("");
			sw->WriteLine("Data Logged Using Monitoring System (c) 2010 Sunny Group");
			sw->Close();
			MessageBox::Show( "File Saved!","Save Complete!",
            MessageBoxButtons::OK, MessageBoxIcon::Exclamation );
		 }

		 if((AttachedState == FALSE) || (AttachedButBroken == TRUE))
		 {
			MessageBox::Show( "Please Connect Monitoring System!","Save Data Error!",
            MessageBoxButtons::OK, MessageBoxIcon::Exclamation );

		 }

	}

Thanks for your respond.

Regards,
nsw1216

 

[horace1]

your example is using Microsoft API specific methods. I would tend to use standard C++ IO as the code is then portable to other compilers and operating systems

 

[nsw1216]

horace1,

Microsoft API? Is there anyway can modify the code to automatically saving the data of my monitoring system ?

 

[horace1]

I use standard C++ stream IO to read/write files. It is simple, e.g. modified from the C++ tutorial on file

// basic file operations
#include <iostream>
#include <fstream>
using namespace std;

int main () {
  int idata=23;
  float fdata=3.14159f;
  ofstream myfile;
  myfile.open ("example.txt");
  myfile << "Writing this to a file.\n";
  myfile << "integer " << idata << " float " << fdata << endl;
  myfile.close();
  return 0;
}

opens the output file example.txt and then uses the << (insertion ) output operator to write data to the file.
the output files looks like

Writing this to a file.
integer 23 float 3.14159

 

[nsw1216]

horace1,

I understand about this. But i can mixed it with the microsoft API coding ? Because I created an interface with microsoft API already.Now I just wanted to modify it to be saving data continuously.

 

[horace1]

I have had no problem mixing the Microsoft GUI API with normal C++ IO, e.g. when using Windows Forms I use cout << to write debug infomation to a console window.
Centainly don't mix call to Microsoft's stream API (StreamWriter etc) with standard C++ stream IO, use one or the other.

 

[nsw1216]

horace1,

means i need to include the header files in order to use the standard C++ stream IO ?

 

[horace1]

yes, you need

#include <iostream>
#include <fstream>
using namespace std;

 

[nsw1216]

horace1,

Thanks for the explanations. But i would like to learn the Microsoft API specific method to save data instead of standard C++ IO stream. Do you know any information or reference about it ?

 

[horace1]

have a look at the Microsoft documentation
StreamWriter Class (System.IO)

also do a web sreach "visual C++ streamwriter"

 

[nsw1216]

horace1,

Thanks for the suggestions.

 

[nsw1216]

horace1,

I got one questions about setting the filename. IS it possible i attach the date into the filename i created ?

 

[horace1]

yes, you can read the system date and time as a character string and create the filename using it, see
localtime - C++ Reference

rememeber that the system saves the date and time when a file is created (but it is still often useful to have it as part of the filename)

 

[nsw1216]

horace1,

Oh I See. Is there any way that using Microsoft API specific method like DateTime::Now or DateTime::Today ?

 

[horace1]

I would guess so but never having used DateTime cannot say for certain - I tend to try to keep to standard C/C++ where possible avoiding platform specific APIs.
All you need is a method which will extract the date from DateTime as a char array or a string that can be used as part of a filename.
look at the the documentation of the API.

 

[nsw1216]

horace1,

ok. thanks.