This problem uses multiple processes and a stored file of information to
address two questions about gemstones.
-
Given a color, select all gemstones of the given color, and print
them in alphabetical order by gemstone name.
-
Print all gemstones, whose hardness and specific gravity values are
within specified ranges.
Some Backgrond concerning Gemstones
Gemstones are attractive forms of rock crystal, commonly used for
decoration and in jewelry. Gemstones also have interesting mineral
properties. Gemstones may be classified in a variety of ways, including
chemical composition, crystal structure, color, specific gravity,
refractive index, and hardness:
-
Chemical Composition: While some gemstones are primarily composed
of atoms of one element (e.g., diamonds are mostly carbon, with coloring
coming from traces of other elements), other gemstones are made up of atoms
of several atoms (e.g., mica molecules include oxygen, hydrogen, silicon,
aluminum, iron, and/or many others). On-line sources of information
include general references (e.g., Common Mineral
Groups) and references to specific minerals (e.g., micas).
-
Color may be classified informally (e.g., red, yellow, etc.) or more
formally by viewing thin slices of mineral crystals through the microscope,
using polarized light (see, for example, Minerals under the
Microscope).
-
Specific Gravity is a measure of the density of a mineral. More
precisely, specific gravity is the ratio of the weight of the mineral in
air to its weight in an equal volume of water. More details are available
from various on-line sources (see, for example, the Mineral and
Gemstone Kingdom's glossary for specific gravity.
-
Refractive Index provides a measure of how much light bends within a
crystal. The higher the refractive index, the more bending and the more
brilliant a crystal is likely to appear. For more information, see various
on-line sources, such as Refractive
Index.
-
Crystal Structure: Crystals typically have one of several standard
shapes or structures, including cubic, tetragonal, orthorhombic, hexagonal,
monoclinic, and triclinic. While the details of such structures are beyond
the scope of this problem, the World Wide Web contains many useful
references, including crystal forms
(at the macro-level).
-
Hardness often is measured on the (nonlinear) Mohs Scale, which
associates a hardness number to each mineral, from 1 (softest) to 10
(hardest):
- Talc
- Gypsum
- Calcite
- Fluorite
- Apatite
- Orthoclase
- Quartz
- Topaz
- Corundum
- Diamond
As a comparison, a fingernail has hardness 2.5, glass has hardness 5.5,
and a steel file has hardness 6.5. Minerals of the same hardness should
not scratch each other, but a mineral of one hardness will scratch minerals
with a lower hardness number.
File gems.txt contains information on
several gemstones, including color, hardness, specific gravity, and
refractive index. Within the file, each line contains information about a
specific gemstone.
Here are a couple of sample lines, and a character 'ruler' to show
how wide the fields are:
11111111112222222222333333333344444444445555555555666666666677777
012345678901234567890123456789012345678901234567890123456789012345678901234
Zircon RED 7.5 4.50 1.95
Topaz YELLOW 8 3.53 1.62
To clarify, the names of the gemstones come first in a line and are
right-justified in a column of width 22 characters. (A gemstone name may
contain multiple words, but the overall width of the name field is 22
characters.) The colors come next, followed by hardness
(on a scale 1 to 10), then specific gravity, and finally refractive index
(generally between 1.3 and 2.5).
Programming Tasks
To answer the questions posed at the start of this question, five programs
are to be utilized, as described below and as illustrated in the following
diagram:
-
Linux utility cat: reads the file gems.txt and print the
contents to stdout.
-
C program control/main:
-
reads input (color desired, lower and upper bounds for desired
hardness, lower and upper bounds for specific gravity) from stdin
-
using pipe/fork, spawns process to run utility cat program,
which will send file data to control/main on a file input
-
using pipe/fork, spawns process to read data from control/main
through a pipe, and to filter only those records that have an
appropriate hardness and specific gravity. (If desired, the
control/main program may send the hardness and specific gravity
ranges to the child through the pipe, before sending the gemstone
data. Alternatively, if desired, these values may be saved as global
variables or transmitted as command-line parameters, so they would be
available to any child process.)
-
using popen, spawns process to read data from control/main
through stdin and filters only records for a designated
color. (If desired, the control/main program may send the desired
color through the pipe, before sending the gemstone data.
Alternatively, if desired, these values may be saved as global
variables or transmitted as command-line parameters, so they would be
available to any child process.)
Linux utility sort: This process, spawned by the process for
filtering by color, put the records in alphabetical order and prints its
results to stdin, the user's monitor.
Altogether,
-
The flow of data from cat to control/main to the
filter by color program to sort to the screen addresses the
first question posed.
-
the flow of data from cat to control/main
to the filter-by-properties program to the screen addresses the second
question posed.
Sample Output
If the user types "GREY" as the color of gemstones, processing should
return a table, such as the following:
Specific Refractive
Gemstone Color Hardness Gravity Index
Alabaster GREY 2 2.32 1.53
Bakelite GREY 2.5 1.28 1.65
Calcite GREY 3 2.7 2.71
Casein GREY 2.5 1.33 1.55
Celluoid GREY 2 1.35 1.50
Chalcedony GREY 7 2.62 1.53
Corundum GREY 9 3.99 3.99
Diamond GREY 10 3.52 3.52
Hematite GREY 6 5.10 5.05
Ivory GREY 2.5 1.80 1.54
Jadeite GREY 7 3.34 3.33
Labradorite GREY 6 2.7 2.70
Marble GREY 3 2.71 1.50
Meerschaum GREY 2 1.50 1.53
Nephrite GREY 3.5 3.00 2.96
Opal GREY 6 2.10 2.10
Quartz GREY 7 2.65 1.55
Quartz GREY 7 3.33 2.65
Talc GREY 1 2.70 2.75
Another possible format might be:
Specific Refractive
Gemstone Name Color Hardness Gravity Index
Alabaster GREY 2 2.32 1.53
Bakelite GREY 2.5 1.28 1.65
Calcite GREY 3 2.70 2.71
Casein GREY 2.5 1.33 1.55
Celluoid GREY 2 1.35 1.50
Chalcedony GREY 7 2.62 1.53
Corundum GREY 9 3.99 3.99
Diamond GREY 10 3.52 3.52
Hematite GREY 6 5.10 5.05
Ivory GREY 2.5 1.80 1.54
Jadeite GREY 7 3.34 3.33
Labradorite GREY 6 2.70 2.70
Marble GREY 3 2.71 1.50
Meerschaum GREY 2 1.50 1.53
Nephrite GREY 3.5 3.00 2.96
Opal GREY 6 2.10 2.10
Quartz GREY 7 2.65 1.55
Quartz GREY 7 3.33 2.65
Talc GREY 1 2.70 2.75
As shown in each example, the gemstone names and properties must appear in
labeled columns. Gemstone names may be either left-justified or
right-justified.
A similar format could be used in printing gemstone information for the
second question.
Note that some gemstones, such as Quartz above, appear several times in the
table, since variations of a gemstone may have different properties.
Problem-specific grading form for
Supplemental Problem 3
