CS157 HW1: Unit Conversion                

Description                

Shockingly, the entire world does not use our splendid inches-feet-miles units of measurement! For this assignment, you will write a program called units.c, which will translate between various units of measurement.                 

Data File                

Your program does not have to handle all possible units. It only has to handle those units given in a data file. This file will have two columns: the unit name, and its value relative to meters.                 

An example of a data file follows:                 

    INCH 0.0254
    FOOT 0.3048
    YARD 0.9144
    MILE 1609.344
    MM 1e-3
    CM 1e-2
    METER 1
    KM 1e3
    AU 149597870700.0

This file indicates that an inch is 0.0254 meters, a foot is 0.3048 meters, and so on. From this, one could deduce that there are 1609.344/0.3048, or 5280, feet in a mile.                 

We will test your program with other similar data files, with different names. Do not assume that all data files have any particular name, or that they will contain exactly those units, or in that order.                 

Sample Run                

Here are several sample runs, using the data file above, which we will call lengths.                 

    % c11 -Wall units.c -o u
    % ./u lengths 12 inch foot
    12.00 inch is 1.00 foot.
    % ./u lengths 30 inch foot
    30.00 inch is 2.50 foot.
    % ./u lengths 1 foot inch
    1.00 foot is 12.00 inch.
    % ./u lengths 1 inch foot
    1.00 inch is 0.08 foot.
    % ./u lengths 1 au mile
    1.00 au is 92955807.27 mile.
    % ./u lengths 1000 meter km
    1000.00 meter is 1.00 km.
    % ./u lengths 1 inch mile
    1.00 inch is 0.00 mile.
    % ./u
    usage: ./u <unitfile> <amount> <from> <to>
    % ./u lengthz 1 inch foot
    ./u: can’t open file lengthz
    % ./u lengths 1 inch feet
    ./u: no such unit "feet"

Requirements                

• Use double variables, rather than float, so that your results will match ours.
• Comment block at the very very very beginning of the file with name/date/purpose of program.
• Comment block at the start of each function, describing what it does.
• The unit values from the file may be inaccurate. Live with it. Do not seek better values.
• All values must be printed with two places after the decimal point.
• The data file will contain no more than fifty lines, each no more than eighty characters long.
• Each unit name in the file will be at most ten characters long.
• Each unit name in the file will be all upper-case letters.
• There may be extra spaces between the fields of the data file.
• If fewer than three arguments are given, then an error message, including the program name from argv[0] must be sent to stderr.
• If the data file can't be opened, then an error message, including the program name from argv[0], and the data file name, must be sent to stderr.
• If a unit name is not found in the data file, then an error message, including the program name from argv[0] and the unit name, must be sent to stderr.
• Case doesn’t matter for units. An argument of “fOo” must match the string “FOO” from the file.
• The output will be ungrammatical, e.g., “3 mile”. That’s ok.
• Your output must be just like the sample, given that data file, and that input.
• You may not use global variables.
• You must close any file that you open.
• Use char constants for char values, not int ASCII values: 'A', not 65.

How to submit your homework:                

Use                 

    ~cs157/bin/checkin HW1 units.c

or web checkin.                 

How to receive negative points:                

Turn in someone else’s work.