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Reference/es_mbb_f64_r

Syntax

int es_mbb_i64_r( struct es_mbb *fb, const char *fieldname, double **pvar );

Arguments

struct es_mbb Field-binding collection.
const char *fieldname Database field name.
double **pvar Reference to 64bit double-precision pointer program variable

Return Codes

ES_ERROR_NONE Success. No errors.
ES_ERROR_INVALIDFIELDTYPE Database field is not 64bit double-precision(ES_FLDTYPE_F64).
ES_ERROR_UNKNOWNFIELD Unknown database field in this class.

Description

Bind by reference the 64bit double-precision program variable referenced by pvar with the database field fieldname. The field-binding fb must have been previously constructed via es_mbb_new().

Binding by reference means that a pointer to fieldname's value is copied to the program variable referenced by pvar during both fetch and update operations. The contents of fieldname may then be read or assigned to directly by de-referencing *pvar.

This is particularly useful for incrementally updating fields which are designated as aggregate values. Database fields are also always zero-initialized which can simplify code.

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