File: gawk.info,  Node: Requesting Values,  Next: Accessing Parameters,  Prev: Updating ERRNO,  Up: Extension API Description

17.4.9 Requesting Values
------------------------

All of the functions that return values from 'gawk' work in the same
way.  You pass in an 'awk_valtype_t' value to indicate what kind of
value you expect.  If the actual value matches what you requested, the
function returns true and fills in the 'awk_value_t' result.  Otherwise,
the function returns false, and the 'val_type' member indicates the type
of the actual value.  You may then print an error message or reissue the
request for the actual value type, as appropriate.  This behavior is
summarized in *note Table 17.2: table-value-types-returned.


                                     Type of Actual Value
--------------------------------------------------------------------------
                        String   Strnum   Number   Regex   Bool     Array   Undefined
----------------------------------------------------------------------------------------
            String      String   String   String   String  String   false   false
            Strnum      false    Strnum   Strnum   false   false    false   false
            Number      Number   Number   Number   false   Number   false   false
Type        Regex       false    false    false    Regex   false    false   false
Requested   Bool        false    false    false    false   Bool     false   false
            Array       false    false    false    false   false    Array   false
            Scalar      Scalar   Scalar   Scalar   Scalar  Scalar   false   false
            Undefined   String   Strnum   Number   Regex   Bool     Array   Undefined
            Value       false    false    false    false   false    false   false
            cookie

Table 17.2: API value types returned