Creating an Icon list of a fixed size
Creating an Icon list of a fixed size |
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The Icon function ``list(n, x)'' creates a list containing n elements, all equal to x. So, for example, this expression sets the variable ``totals'' to a list containing ten zeroes:
totals := list ( 10, 0 );
You can also omit the second argument to the ``list()''
function, and each element will be undefined (that is, set to the null
value; see
`How does the null value work in Icon?'). For example, this expression sets the
variable ``winners'' to a list of 86 copies of
the null value ``&null'':
winners := list ( 86 );
Warning! This statement does not do what you think:
danger := list ( 5, [] );
You'd think it would set up a list containing five empty lists, but it
doesn't. It sets up a list containing five pointers
to the same empty list. Pages 76--77 of the Icon book
have a good discussion of pointers; see
`References for the Icon programming language'.