gawk: Array Functions
16.4.11.2 Array Functions
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The following functions relate to individual array elements:
'awk_bool_t get_element_count(awk_array_t a_cookie, size_t *count);'
For the array represented by 'a_cookie', place in '*count' the
number of elements it contains. A subarray counts as a single
element. Return false if there is an error.
'awk_bool_t get_array_element(awk_array_t a_cookie,'
' const awk_value_t *const index,'
' awk_valtype_t wanted,'
' awk_value_t *result);'
For the array represented by 'a_cookie', return in '*result' the
value of the element whose index is 'index'. 'wanted' specifies
the type of value you wish to retrieve. Return false if 'wanted'
does not match the actual type or if 'index' is not in the array
(Table 16.1 table-value-types-returned.).
The value for 'index' can be numeric, in which case 'gawk' converts
it to a string. Using nonintegral values is possible, but requires
that you understand how such values are converted to strings (
Conversion); thus, using integral values is safest.
As with _all_ strings passed into 'gawk' from an extension, the
string value of 'index' must come from 'gawk_malloc()',
'gawk_calloc()', or 'gawk_realloc()', and 'gawk' releases the
storage.
'awk_bool_t set_array_element(awk_array_t a_cookie,'
' const awk_value_t *const index,'
' const awk_value_t *const value);'
In the array represented by 'a_cookie', create or modify the
element whose index is given by 'index'. The 'ARGV' and 'ENVIRON'
arrays may not be changed, although the 'PROCINFO' array can be.
'awk_bool_t set_array_element_by_elem(awk_array_t a_cookie,'
' awk_element_t element);'
Like 'set_array_element()', but take the 'index' and 'value' from
'element'. This is a convenience macro.
'awk_bool_t del_array_element(awk_array_t a_cookie,'
' const awk_value_t* const index);'
Remove the element with the given index from the array represented
by 'a_cookie'. Return true if the element was removed, or false if
the element did not exist in the array.
The following functions relate to arrays as a whole:
'awk_array_t create_array(void);'
Arrays:: for a discussion of how to create a new array and add
elements to it.
'awk_bool_t clear_array(awk_array_t a_cookie);'
Clear the array represented by 'a_cookie'. Return false if there
was some kind of problem, true otherwise. The array remains an
array, but after calling this function, it has no elements. This
is equivalent to using the 'delete' statement (Delete).
'awk_bool_t flatten_array_typed(awk_array_t a_cookie,'
' awk_flat_array_t **data,'
' awk_valtype_t index_type,'
' awk_valtype_t value_type);'
For the array represented by 'a_cookie', create an
'awk_flat_array_t' structure and fill it in with indices and values
of the requested types. Set the pointer whose address is passed as
'data' to point to this structure. Return true upon success, or
false otherwise. Flattening Arrays, for a discussion of
how to flatten an array and work with it.
'awk_bool_t flatten_array(awk_array_t a_cookie, awk_flat_array_t **data);'
For the array represented by 'a_cookie', create an
'awk_flat_array_t' structure and fill it in with 'AWK_STRING'
indices and 'AWK_UNDEFINED' values. This is superseded by
'flatten_array_typed()'. It is provided as a macro, and remains
for convenience and for source code compatibility with the previous
version of the API.
'awk_bool_t release_flattened_array(awk_array_t a_cookie,'
' awk_flat_array_t *data);'
When done with a flattened array, release the storage using this
function. You must pass in both the original array cookie and the
address of the created 'awk_flat_array_t' structure. The function
returns true upon success, false otherwise.