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An important aspect of arrays to remember is that array subscripts are always strings. If you use a numeric value as a subscript, it will be converted to a string value before it is used for subscripting (see section Conversion of Strings and Numbers).
This means that the value of the CONVFMT can potentially
affect how your program accesses elements of an array. For example:
a = b = 12.153
data[a] = 1
CONVFMT = "%2.2f"
if (b in data)
printf "%s is in data", b
else
printf "%s is not in data", b
should print `12.15 is not in data'. The first statement gives
both a and b the same numeric value. Assigning to
data[a] first gives a the string value "12.153"
(using the default conversion value of CONVFMT, "%.6g"),
and then assigns 1 to data["12.153"]. The program then changes
the value of CONVFMT. The test `(b in data)' forces b
to be converted to a string, this time "12.15", since the value of
CONVFMT only allows two significant digits. This test fails,
since "12.15" is a different string from "12.153".
According to the rules for conversions
(see section Conversion of Strings and Numbers), integer
values are always converted to strings as integers, no matter what the
value of CONVFMT may happen to be. So the usual case of
for (i = 1; i <= maxsub; i++)
do something with array[i]
will work, no matter what the value of CONVFMT.
Like many things in awk, the majority of the time things work
as you would expect them to work. But it is useful to have a precise
knowledge of the actual rules, since sometimes they can have a subtle
effect on your programs.
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