EXTRACT

EXTRACT(dynarray,f[,v[,s]])

dynarray	An expression that resolves to a dynamic array.
f	An expression that resolves to an integer specifying the Field level of the dynamic array from which to access the data. Fields are counted from 1.
v	Optional — An expression that resolves to an integer specifying the Value level of the dynamic array from which to access the data. Values are counted from 1 within a Field.
s	Optional — An expression that resolves to an integer specifying the Subvalue level of the dynamic array from which to access the data. Subvalues are counted from 1 within a Value.

The EXTRACT function returns the data value from one element of a dynamic array. Which element to access is specified by the f, v, and s integers. For example, if f=2 and v=3, this means access the third value from the second field. If f=2 and v is not specified, this means to access the entire second field.

If lower level delimiters exist in dynarray, setting an upper level to 0, the null string, or a non-numeric value is equivalent to setting it to 1.

If lower level delimiters do not exist in dynarray, setting this non-existent lower level to 1, 0, the null string, or a non-numeric value has no effect on retrieving the data value in the level above it.

You can also use the <> operator to extract an element value from a dynamic array. For further details, see the Dynamic Arrays page of this manual.

The following example uses the EXTRACT function to access the second value from the first field of a dynamic array:

cities="New York":@VM:"London":@VM:
"Chicago":@VM:"Boston":@VM:"Los Angeles"
PRINT EXTRACT(cities,1,2)
    ! Returns: "London"

cities="New York":@VM:"London":@VM:
"Chicago":@VM:"Boston":@VM:"Los Angeles"
PRINT EXTRACT(cities,1,2)
PRINT EXTRACT(cities,0,2)
PRINT EXTRACT(cities,"",2)

cities="New York":@VM:"London":@VM:
"Chicago":@VM:"Boston":@VM:"Los Angeles"
PRINT EXTRACT(cities,1,2,0)
PRINT EXTRACT(cities,1,2,1)
PRINT EXTRACT(cities,1,2,"")

UniData systems differ in how they handle f, v, and s arguments set to 0. The $OPTIONS ATTR.0IS1 (“zero is one”) provides support for this UniData feature. UniData systems ignore v and s arguments that are set to a negative number.