In this assignment you will write a C filter program that formats a stream of input numbers into nicely organized columns. Your program will make use of command-line arguments andenvironment variables to determine parameters for the output formatting.

Write a C program called filter.c that reads from standard input and writes to standard output. The input to your program will be decimal numbers separated by white space. The output of your program will be the input numbers formatted into columns.

The decimal point of every number in a column must line up. The number of digits after a decimal point is called the precision of a decimal number. All the numbers in the output will have the same precision. The default precision for your output is 13 decimal places. If there is an environment variable called PRECISION, then the value of that variable overrides the default precision. If there is a command line parameter, then that command line parameter overrides both the environment variable (if there is one) and the default value of precision.

The default number of output columns for your output is three. If there is an environment variable called COLUMNS, then the value of that variable overrides the default number of columns. If there is a second command line parameter, then that command line parameter overrides both the environment variable (if there is one) and the default number of columns.

Your program should use the Standard C Library function getenv() to see if there are environment variables named PRECISION or COLUMNS. If either one exits, its string value should be converted to an integer value by using the Standard C Library function atoi()("atoi" is an abbreviation of "ascii to integer")..

Your program will read in values from standard input by using the Standard C Library functionscanf() and its associated formatting strings.

Your program will write formatted output numbers (with the decimal points lined up and the proper number of decimal digits) to standard output by using the Standard C Library functionprintf() and its associated formatting strings. (Hint: You will need to make use of the *character in your format strings.)

Formatted input and output is not as hard as it might seem by looking at the last few references. After a few examples, you quickly get the hang of it.

Here are a couple of examples. If the input stream to your program looks like this:

INPUT :

5163.1575670644243 6806.8180791650138 8977.2739646595655 2598.0792870876185 7162.5237586596268 6691.2041993469038 1043.6422009949033 6922.8216193121125 3.0480056154058 9926.6081118198181 100.3082369457076 5135.1567125461588 7808.2382885219886 1439.6542863246559 249.6179692983795 214.0065309610279 9280.5883968626968 2687.3871883297220 7612.8426770836513 6644.2027649769589 8364.5604419080173 4740.7550279244360 254.6181218909269 2500.3814813684498 2293.6803491317482 835.3306680501725 5962.7923215430155 9622.5988341929387 57.3069246498001 1557.9630726035341 8398.5614795373385 5958.4870143742182 2568.3835566270945 9935.9135715811644 3410.1040681173131 982.0299691763055 8393.5613269447913 9066.2766808069100 4896.4546037171549 7597.8422193060087 8551.5661488692895 1076.6432081057162 1911.3635059663686 7586.8418836024048 9282.8936429944770 4696.1433149204995 1388.0423596911528 1936.3642689291055 3408.4091921750542 3556.4137089144565 9241.8923917355878 5003.4578691976685 3366.7130954924160 4270.1303140354621 620.6292916653950 4700.7538071840572 1766.0538956877347 441.6238288521989 8153.8591875972779

OUTPUT:

5163.1575670644243 6806.8180791650138 8977.2739646595655 2598.0792870876185 7162.5237586596268 6691.2041993469038 1043.6422009949033 6922.8216193121125 3.0480056154058 9926.6081118198181 100.3082369457076 5135.1567125461588 7808.2382885219886 1439.6542863246559 249.6179692983795 214.0065309610279 9280.5883968626968 2687.3871883297220 7612.8426770836513 6644.2027649769589 8364.5604419080173 4740.7550279244360 254.6181218909269 2500.3814813684498 2293.6803491317482 835.3306680501725 5962.7923215430155 9622.5988341929387 57.3069246498001 1557.9630726035341 8398.5614795373385 5958.4870143742182 2568.3835566270945 9935.9135715811644 3410.1040681173131 982.0299691763055 8393.5613269447913 9066.2766808069100 4896.4546037171549 7597.8422193060087 8551.5661488692895 1076.6432081057162 1911.3635059663686 7586.8418836024048 9282.8936429944770 4696.1433149204995 1388.0423596911528 1936.3642689291055 3408.4091921750542 3556.4137089144565 9241.8923917355878 5003.4578691976685 3366.7130954924160 4270.1303140354621 620.6292916653950 4700.7538071840572 1766.0538956877347 441.6238288521989 8153.8591875972779 

On the other hand, if we use seven columns and only two digits of precision, the same input should produce the following output.

5163.16 6806.82 8977.27 2598.08 7162.52 6691.20 1043.64 6922.82 3.05 9926.61 100.31 5135.16 7808.24 1439.65 249.62 214.01 9280.59 2687.39 7612.84 6644.20 8364.56 4740.76 254.62 2500.38 2293.68 835.33 5962.79 9622.60 57.31 1557.96 8398.56 5958.49 2568.38 9935.91 3410.10 982.03 8393.56 9066.28 4896.45 7597.84 8551.57 1076.64 1911.36 7586.84 9282.89 4696.14 1388.04 1936.36 3408.41 3556.41 9241.89 5003.46 3366.71 4270.13 620.63 4700.75 1766.05 441.62 8153.86