/**
	Export worksheet to a ASCII file
	Parameters: 
		lpcszFilename = a full path file name
		dwCntrl = can be the following value(defined in OC_Const.h):
					WKS_EXPORT_HEADING	0x0001	// col name
					WKS_EXPORT_ALL		0x0002	// ignore c1c2r1r2
					WKS_EXPORT_LABELS	0x0004	// col label
					WKS_EXPORT_SELECTED 0x0008	// only selected cols
		lpcszSeparator = the separator in the data file. The default separator is "\t".
		nR1 = first row in the data range to be included with the data file.
		nC1 = first column in the data range to be included with the data file.
		nR2 = last row in the data range to be included with the data file.
		nC2 = last column in the data range to be included with the data file.
	Return: 
		On error, returns -1, otherwise returns the exported file size.
	Example:
	void test_export_ascii()
	{
		Worksheet wks = Project.ActiveLayer();
		if(wks)
		{
			string strFile = GetSaveAsBox("*.dat");
			wks.ExportASCII(strFile, WKS_EXPORT_ALL);
		}
	}

*/
	int ExportASCII(LPCSTR lpcszFilename, DWORD dwCntrl, char cSeparator = '\t', int nR1 = 0, int nC1 = 0, int nR2 = -1, int nC2 = -1);