The Bourne shell restricted variables to single values.
The C shell imposes no such limit.
It provides the user with the use of array variables, which are
variables that contain two or more discreet values.
Ignoring proper C shell notation for a moment, an example of an array
would be a variable called alphabet which contained each of the
26 letters A through Z.
To access a particular letter the variable might be followed by the
number of the sequence which contained the desired letter.
For example, the letter C might be referred to as
alphabet(3), while Z would be referred to as
alphabet(26).
An array is a nice way to store related elements which could be
accessed under the same name.
In the C shell, array variables can be set as follows.
All of the array elements can be set at one time by enclosing the list
with parentheses and separating the elements with white space (usually
spaces).
For example, to set an array of pets:
% set PETS=(Cat Dog Goldfish Horse Boa Hamster)
To access an element of a variable the variable name is followed by square brackets containing the element number:
% echo $PETS[3] goldfish % echo $PETS[3-5] Goldfish Horse Boa
The example illustrates how more than a single element can be accessed
at once using the - operator.
If this operator is placed before or after a number it will access all
of the elements up to and including or including to the end of the
list respectively.
For example,
% echo $PETS[-3] Cat Dog Goldfish
The entire array variable list can be accessed by placing an *
in the square brackets.
Table 4.2 summerizes the ways to access array elements:
Table 4.2: Ways to access array elements.