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216 10 Transforming with Traditional Programming Languages

Number of records: 2

Average BMI: 25.665

BMI Variance: 137.28245

BMI Standard Deviation: 11.7167593642611

As usual, there are many ways to abbreviate statements in this program.

One common abbreviation is to omit some of the parentheses in the foreach

statement. Thus

foreach $m (sort(keys(%count))) {

can be written

foreach $m (sort keys %count) {

One could also abbreviate it to

foreach (sort keys %count) {

in which case the scalar holding the key is$_instead of$m.

Although hashes use a different notation than arrays, one can use hashes

to implement arrays. All one needs to do is write the index using braces

instead of brackets. Thus one would write$x{2}instead of$x[2].Using

hashes instead of arrays is convenient when the indexes are not consecutive

or do not start at 0. The one place where one must be careful when using

hashes is when one is iterating. By default thesortfunction sorts the keys

as strings. If the keys are actually numbers, the order will look rather strange.

For example, “10” precedes “2” as strings. To sort in numerical order specify

{$a<=> $b }after the sort function. For example, if%xis a hash whose

keys are numerical, then the following will print the values in numerical

order:

foreach $i (sort { $a <=> $b } keys %x) {

print("$i: $x{$i}\n");

}

Many other sorting orders can be used by varying the sort order used in the

braces after the sort function. The default order is dictionary ordering which

uses thecmpoperator.