Variable and Array Assignment
Variables can be assigned a value with an =
sign. For example:
FS = ","
Expressions using the operators +
, -
,
/
, and %
(modulo) can be assigned to
variables.
Arrays can be created with the split()
function (described later), or they
can simply be named in an assignment statement. Array elements can be subscripted with
numbers (array
[1]
, ..., array
[
n
]
) or with strings. Arrays
subscripted by strings are called associative
arrays.[*] For example, to count the number of widgets you have,
you could use the following script:
/widget/ { count["widget"]++ } Count widgets END { print count["widget"] }Print the count
You can use the special for
loop to read all the elements of an associative array:
for (item in array)
process
array[item]
The index of the array is available as item
, while the value of an element of the
array can be referenced as array[item]
.
You can use the in
operator
to test that an element exists by testing to see if its index exists.
For example:
if (index in array) ...
tests that array[index]
exists, but you cannot use it to test the value of the element
referenced by array[index]
.
You can also delete individual elements of the array using the
delete
statement. (See also the
delete entry in the section "Alphabetical Summary of awk
Functions and Commands,” later in this chapter.)
[*] In fact, all arrays in awk are associative; numeric subscripts are converted to strings before using them as array subscripts. Associative arrays are one of awk
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