QMExtract()

The QMExtract() function extracts a field, value or subvalue from a dynamic array. It is analogous to the QMBasic field extraction operator or the EXTRACT() function.

Format

VB	QMExtract(ByVal Src as String, ByVal Fno as Integer, ByVal Vno as Integer, ByVal Svno as Integer) as String

C	char * QMExtract(char * Src, int Fno, int Vno, int Svno)

where

Src	is the dynamic array to be processed

Fno	is the number of the field to be extracted. If less than 1, 1 is assumed

Vno	is the number of the value to be extracted. If less than 1, the entire field is extracted.

Svno	is the number of the subvalue to be extracted. If less than 1, the entire value is extracted.

The QMExtract() function returns the given field, value or subvalue from the source string. If the required item is not found, a null string is returned.

Examples

Rec = QMRead(fClients, ClientNo, ErrNo)

CliAddr = QMExtract(Rec, 4, 0, 0)

Rec = QMRead(fClients, ClientNo, ErrNo);

CliAddr = QMExtract(Rec, 4, 0, 0);

The above program fragment reads the record identified by ClientNo from the file open as fClients and then extracts field 4 from it. A real program should test the ErrNo status from the read to determine if the action was successful.

Note that the C example leaves variables CliAddr pointing to a dynamically allocated memory area that must be released using QMFree() when no longer needed.