C / C++ / MFC

// both of these prototypes (basicaly) mean the same thing.
extern double pressure(double x);
double pressure(double x);

// structure representing a binary data record
struct tagMyDataRecord { int H_ft, kh_md, kv_md; float visc_cp, por, ct_psi; };
// a simple array of data records
tagMyDataRecord recArray[100];
// reading data members
inputdeck>>recArray[i].H_ft>>recArray[i].kh_md>>recArray[i].kv_md>>recArray[i].visc_cp>>recArray[i].por>>recArray[i].ct_psi;

// structure representing a binary data record
struct tagMyDataRecord { int H_ft, kh_md, kv_md; float visc_cp, por, ct_psi; };

double pressure(tagMyDataRecord* precArray, int nSize)
{
	double RetValue = 0.0; // needed to hold result
	for( int i=0; i<nSize; ++i )
	{ /* do your calculations in this loop */ }
	return RetValue;
}

void CKuchukDlg::OnAnalyze() 
{
	// Try to open inupt file
	ifstream inputdeck;
	inputdeck.open("input.txt", ios::in);
	
	if (inputdeck.fail())
	{
		//cout<<"Error With Files!";
		AfxMessageBox("Error: Could not open data file!", MB_ICONSTOP);
		return; // we cann't do any thing else
	}	

	// Skip title lines
	inputdeck.ignore(60, '\n');
	inputdeck.ignore(60, '\n');
	
	// Read numaric data from file
	int recCount = 0;
	tagMyDataRecord recArray[100];
	while( recCount < 100 && !(inputdeck.fail() || inputdeck.eof()) )
	{
		inputdeck>>recArray[i].H_ft>>recArray[i].kh_md>>recArray[i].kv_md;
		inputdeck>>recArray[i].visc_cp>>recArray[i].por>>recArray[i].ct_psi;
		++recCount;
		
	}
		
	if (inputdeck.fail())
	{
		AfxMessageBox("Error: Data file read!", MB_ICONSTOP);
		return; // we cann't do any thing else
	}

	// Process data
	double result = pressure(recArray, recCount);
	if (!result)
	{
		AfxMessageBox("Warning: Pressure = 0.0, this may be an error!", MB_ICONSTOP);
	}

	// Open output file
	ofstream outputdeck;
	outputdeck.open("output.txt", ios:out);
	
	if (ofstream.fail())
	{
		AfxMessageBox("Error: Could not open output file!", MB_ICONSTOP);
		return; // we cann't do any thing else
	}	

	// Copy results to output file
	outputdeck<<"Pressure"<<press<<endl;
	AfxMessageBox("Output file Generated!", MB_ICONINFORMATION|MB_OK);
}

if( 'a' <= nChar && nChar <= 'z' )
    nChar = 'A' + (nChar - 'a');

nChar = toupper(nChar);