MACROMEDIA COLDFUSION 4.5-CFML LANGUAGE Manuale Utente Scaricare il pdf (Pagina 30)

30 CHAPTER 30 Extending ColdFusion with CFX

Listing 30.5 (continued)

// Retrieve value of VARIABLE attribute

LPCSTR lpszVariable = pRequest->GetAttribute(“VARIABLE”) ;

// Make sure a VARIABLE attribute was actually passed to the tag

if ( pRequest->AttributeExists(“COLUMN”)==FALSE ) {

pRequest->ThrowException(

“Error in CFX_ComputeStandardDeviation Tag”,

“No COLUMN attribute specified.”);

}

// Retrieve value of VARIABLE attribute

LPCSTR lpszColumn = pRequest->GetAttribute(“COLUMN”) ;

// Retrieve the query specified in the tag’s QUERY attribute

CCFXQuery* pQuery = pRequest->GetQuery();

// Make sure a query was actually passed to the tag

if ( pQuery == NULL ) {

pRequest->ThrowException(

“Error in CFX_ComputeStandardDeviation Tag”,

“No QUERY provided.”);

}

// Find the index position of the column named in the COLUMN attribute

int colIndex = pQuery->GetColumns()->GetIndexForString( lpszColumn );

// If the column specified in COLUMN attribute does not exist in query

if ( colIndex == CFX_STRING_NOT_FOUND ) {

pRequest->ThrowException(

“Error in CFX_ComputeStandardDeviation Tag”,

“The COLUMN attribute does not match up to a column in the query.”);

}

/* FINISHED WITH ATTRIBUTE VALIDATION */

// Local variables

double dTotal = 0;

double dMean = 0;

double dStdDev = 0;

double dSumSq = 0;

double dVariance = 0;

int iValueCount = 0;

// Compute the total of all the numbers in the data set

for ( int Row = 1; Row <= pQuery->GetRowCount(); Row++) {

// Get the value (as a string) from the query

LPCSTR thisVal = pQuery->GetData(Row, colIndex);

// Assuming the value is not an empty string

if ( strlen(thisVal) > 0) {

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MACROMEDIA COLDFUSION 4.5-CFML LANGUAGE Manuale Utente Pagina 30