1. Programming Assignment #1 12-Month Calendar—
Professor Hugh C. Lauer CS-2303, System Programming Concepts
(Slides include materials from The C Programming Language, 2nd edition, by Kernighan and Ritchie, Absolute C++, by Walter Savitch, The C++ Programming Language, Special Edition, by Bjarne Stroustrup, and from C: How to Program, 5th and 6th editions, by Deitel and Deitel)
CS-2303, A-Term 2012
PA1 — Twelve Month Calendar

2. PA1 — Twelve Month Calendar
Goals and Objectives
Develop a simple C program on a Linux platform based on your Java skills
Become familiar with C idiosyncrasies pertaining to loops, switches, and conditional statements
Learn to use formatted input and output in C
CS-2303, A-Term 2012
PA1 — Twelve Month Calendar

3. Display a 12-Month Calendar
Prompt for a non-negative year number (e.g., 2012)
Determine starting day-of-the-week and whether or not it is a leap year
Print calendar for twelve months for that year
CS-2303, A-Term 2012
PA1 — Twelve Month Calendar

4. Sample Output (fragment)
January Sun Mon Tue Wed Thu Fri Sat February Sun Mon Tue Wed Thu Fri Sat …
Two spaces between days
Note – right justified under day of week
CS-2303, A-Term 2012
PA1 — Twelve Month Calendar

5. PA1 — Twelve Month Calendar
Implementation
Loop statements — similar to Java
for loop
while loop
Nested loops
Conditional statements — also similar to Java
if-else statement
switch and break statements
Function declarations — similar to Java, but not part of any class
Calling functions is similar to Java
Formatted input and output — very different from Java
CS-2303, A-Term 2012
PA1 — Twelve Month Calendar

6. PA1 — Twelve Month Calendar
Hints
Think through the data you need to keep track of
Which month and how many days per month
Which day of week and when to start new line
Think through how to organize loops to
Cycle through the months
Cycle through the days within a month
Communicate day of week from one month to next
Ask questions next time!
CS-2303, A-Term 2012
PA1 — Twelve Month Calendar

7. PA1 — Twelve Month Calendar
printf() & scanf()
Prints a string in which each conversion specifier is replaced with value of corresponding argument
int printf("string in double quotes", arg1, arg2, arg3, …);
Conversion specifier:–
Part of the "string in double quotes"
Begins with '%' character
Describes how to print one argument
ith conversion specifier in string says how to print argi
Resulting string printed on stdout
Returns number of characters printed!
Note – the "... " means that the number of arguments is open-ended
CS-2303, A-Term 2012
PA1 — Twelve Month Calendar

8. PA1 — Twelve Month Calendar
printf() (continued)
%d, %i — decimal number
%u — unsigned decimal number
%c — character
%s — string
%f — floating point number
e.g.,
%e, E — floating point number
e.g., e+8 or E+8
%% — a single ‘%’ character
See K&R textbook for full list (pp 154, 244)
CS-2303, A-Term 2012
PA1 — Twelve Month Calendar

9. printf() Optional Controls
^ – minimum field width
Padded on left
^ – precision of number
or minimum number of digits for decimal number
%.12s
^ – width of string
%-6.4f
^ – indicates left justify
Padded on right
CS-2303, A-Term 2012
PA1 — Twelve Month Calendar

10. PA1 — Twelve Month Calendar
printf() Examples
int j = 24;
float twoPi = 2 * pi;
printf("j=%d, k=%f\n", j, twoPi );
Output
j=24, k=
Return from printf() = 16
printf("%4d %4d %4d %6d", 1, 10, 100, 1000);
CS-2303, A-Term 2012
PA1 — Twelve Month Calendar

11. PA1 — Twelve Month Calendar
scanf()
Reads input, decomposes into individual variables
Opposite of printf()
scanf("string in double quotes", &arg1, &arg2, &arg3, …);
Arguments must be locations – use ‘&’
Converts input string according to scan string, stores in variables
Returns number of matched and stored items
Or the value EOF if end of file is encountered
Stops at end of argument string or when no match is found
CS-2303, A-Term 2012
PA1 — Twelve Month Calendar

12. PA1 — Twelve Month Calendar
scanf() Examples
int i;
double x;
char c;
scanf("%d%f%c", &i, &x, &c);
Looks first for an integer
Skips white space, including newline characters
Looks next for a floating point
Looks next for a single character
Does not skip white space; returns the first character it finds
CS-2303, A-Term 2012
PA1 — Twelve Month Calendar

13. PA1 — Twelve Month Calendar
scanf() Formats
%d — any decimal number
%u — an unsigned integer
%c — character
White space not skipped
%e, f, g — floating point number
%s — string
Defer to later in the course
%% — matches a single ‘%’ character
Any other character
Matches that character
CS-2303, A-Term 2012
PA1 — Twelve Month Calendar

14. PA1 — Twelve Month Calendar
scanf() Formats
Must specify 'h' or 'l' indicating short or long integer, float vs. double
%d — any decimal number
%u — an unsigned integer
%c — character
White space not skipped
%e, f, g — floating point number
%s — string
Defer to later in the course
%% — matches a single '%' character
Any other character
Matches that character
CS-2303, A-Term 2012
PA1 — Twelve Month Calendar

15. PA1 — Twelve Month Calendar
Summary of Assignment
Prompt user for a non-negative year number (e.g., 2012)
Determine starting day-of-the-week and whether or not it is a leap year
Print calendar for twelve months for that year
CS-2303, A-Term 2012
PA1 — Twelve Month Calendar

16. PA1 — Twelve Month Calendar
Submission
Submit on Turnin as PA1
Program name PA1.c
Project value:– 20 points
Rules:–
Program must compile without warnings
On CCC systems
Program must be named PA1.c
CS-2303, A-Term 2012
PA1 — Twelve Month Calendar

17. Questions on Assignment?
Digression on Loop Invariants
CS-2303, A-Term 2012
PA1 — Twelve Month Calendar