3.1. Accessing Elements of an ArrayIf you've used arrays in another language,you won't be surprised to find Perl provides a way to subscript an array to refer to an element by a numeric index. The array elements are numbered using sequential integers,beginning at zero and increasing by one for each element,like this: $fred[0] = "yabba"; $fred[1] = "dabba"; $fred[2] = "doo"; The array name (in this case,"fred") is from a completely separate namespace than scalars use. You could have a scalar variable named $fred in the same program. Perl treats them as different things and doesn't get confused.[*] (Your maintenance programmer might be confused though,so don't capriciously make all of your variable names the same.)
You can use an array element like $fred[2] in every place[] where you could use any other scalar variable like $fred. For example,you can get the value from an array element or change that value by the same sorts of expressions we used in the previous chapter:
print $fred[0]; $fred[2] = "diddley"; $fred[1] .= "whatsis"; Of course,the subscript may be any expression that gives a numeric value. If it's not an integer,it'll automatically be truncated to the next lower integer: $number = 2.71828; print $fred[$number - 1]; # Same as printing $fred[1] If the subscript indicates an element that would be beyond the end of the array,the corresponding value will be undef. This is the same as ordinary scalars; if you've never stored a value into the variable,it's undef. $blank = $fred[ 142_857 ]; # unused array element gives undef $blanc = $mel; # unused scalar $mel also gives undef |
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