Zeller$$s congruence $($source:Click$\_$here$\_$for$\_$more$)$ is an algorithm devised by Christian Zeller to calculate

the day of the week for any calendar date. For today$$s Gregorian calendar, Zeller$$s congruence is

G $=($q $+($m $+1)13$

$5+$ U $+$ U

$4+$ V

$42$ V $)$ mod $7(1)$

where G is the day of the week $(0$ means Saturday, $1$ means Sunday, $2$ means Monday, $...),$ q is the day of

the month $(1<=$ q $<=31),$ m is the month $(1<=$ m $<=12),$ and y is the year of the calendar date $(1582<=$ y $<=2099).$

Further, the above equation distinguishes V as the century $($that is$,$ V $=$ y

$100),$ and U as the year of

the century $($that is$,$ U $=$ y mod $100).$

Finally, there is an exception in Zeller$$s congruence for the months of January and February which need to

be counted as month $13$ and $14,$ respectively, of the previous year. Thus, if m $=1$ or m $=2,$ then we need to

add $12$ months to the value of m$,$ and subtract $1$ year from y before we feed the values into the above equation.

Your weekday calculation program should contain the following sections:

$3\mathrm{.}1$ Input Section:

Prompt the user to enter a valid calendar date in the following format:

Please enter a calendar date:

Day, q $=17$

Month, m $=1$

Year, y $=2024$

We assume that the user will always enter proper input values, e$.$g$.$ m$,$ q and y will always be inputted

within the ranges outlined after Eqn. $(1).$ Therefore, there is no need to handle any invalid input in your

program.

$3\mathrm{.}2$ Data Preprocessing:

Deal with the exception for the months of January and February: if m $<3$ then add $12$ to m and subtract

$1$ from y$.$

$3\mathrm{.}3$ Computation:

Use Zeller$$s congruence.

Hint: The floor function is implicit in any integer division. That is$,$ if a and b are both integer variables,

then $$ a

b $=$ a

b $.$

$3\mathrm{.}4$ Output Section:

For the program output, you should print a numerical identifier $(06)$ to represent the computed weekday,

and you should also print the result as a regular text string, i$.$e$.$ Saturday, Sunday, Monday, $...,$ or Friday.

For the example above, the output should look as follows:

$3$

For the calendar date $1/17/2024,$ the day of the week is $4.$

This is a Wednesday.

The bold lines in steps $3\mathrm{.}1.$ and $3\mathrm{.}4.$ are what you should observe on the terminal.

You should save your program code in file named weekday.c$,$ you should also prepare a text file week$-$

day.txt briefly explaining how you designed your program and any hardships faced $($if any$),$ and prepare a

typescript weekday.script which shows that you compile your program $($see section below for compilation

details$)$ and run it$.$ Use the following dates as inputs for your typescript:

$1/17/2024($the deadline for this assignment$),$

$1/1/2025($next New Year$$s Day$),$ and

$10/4/1965($the first day of classes at UCI$).$

For instructions on how to create a typescript, see Section $6$ Typescript at the end of this document.

$4$ Compiling Your Code

To test your program, it must be compiled with the gcc command. This command will report any errors in

your code. To call gcc$,$ use the following template:

zuma$\%$ gcc sourcefile $-$o targetfile

Then, simply execute the compiled file by typing the following:

zuma$\%./$targetfile

Below is an example of how you will compile and execute the "weekday" program:

zuma$\%$ gcc weekday.c $$std$=$c$11-$Wall $-$o weekday

zuma$\%./$weekday

NOTE: If you encounter this error: zuma$\%$ cc$1$: error: unrecognized command line option $"-$std$=$c$11"$

Then use this command before using gcc: zuma$\%$ scl enable devtoolset$-7$ tcsh

$5$ Submit Your Work

To submit your work, you have to be logged in to one of the following servers, zuma or crystalcove. Below

is a checklist of the files you should have.

In the hw$1$ directory, you should have the following files in your Linux account:

$$ weekday.c

$$ weekday.txt

$$ weekday.script

We do require these exact file names $($i$.$e$.$ do not modify the file names$).$ If you use different file names,

we will not see your files for grading. Now, you should change the current directory to the parent directory

containing the hw$1$ directory. Then type the command:

zuma$\%$ ~eecs$22/$bin$/$turnin$.$sh

which will guide you through the submission process.

You will be asked if you want to submit the script file. Type yes or no$.$ If you type $$n$$ or $$no$$ or

just plain return, they will be ignored and be taken as a no$.$ You can keep using the same command to

$4$

update your submitted files until the submission deadline. After the submission deadline, you CANNOT

modify the submitted files anymore