CPSC 215 Assignment 2

Assignment 2

Objectives:

To get an idea of practical C usage, including:

I/O processing (parsing)
pointer operations (pass-by-reference, pointer arith.)
memory allocation/de-allocation (malloc, free)
stack object usage (use of struct and of own Stack object)
multi-conditional processing (switch statement)
ordinal precedence and evaluation (enum)

Supplemental:

To get a feel for Makefiles.

Due date:

02/08/01

Description:

Design a simple calculator program to evaluate simple mathematical expressions, e.g., 2 * 4 + 3.
Use string processing operations to parse the character string input (you'll need to distinguish between numerical values and mathematical operators such as ^, *, /, +, -).
Use the stack ADT to:
1. convert the infix expression into postfix (reverse Polish notation)
2. evluate the postfix expression
Break up your main program file into 4 modules: main.c, stk.c, mystring.c, cal.c, with their corresponding .h header files.
Create a Makefile for your project.

Sample output:

	1 - 2 - 3 * 4 ^ 5 * 6 / 7 ^ 2 ^ 2
	infix: 1 - 2 - 3 * 4 ^ 5 * 6 / 7 ^ 2 ^ 2
	postfix: 1  2  -  3  4  5  ^  *  6  *  7  2  2 ^  ^  /  -
	-8.677
	2 * 4 + 3
	infix: 2 * 4 + 3
	postfix: 2  4  *  3 +
	11.000
	4 + 3 * 2
	infix: 4 + 3 * 2
	postfix: 4  3  2 *  +
	10.000
	2 * (3 + 4)
	infix: 2 * (3 + 4)
	postfix: 2  3  4 +  * 
	14.000
	(3 + 4) * 2
	infix: (3 + 4) * 2
	postfix: 3  4 +   2 * 
	14.000
	2 ^ 3 ^ 3
	infix: 2 ^ 3 ^ 3
	postfix: 2  3  3 ^  ^
	134217728.000
	3 * 2 ^ 5 - 1
	infix: 3 * 2 ^ 5 - 1
	postfix: 3  2  5  ^  *  1 -
	95.000
	1 + 2 * 3 ^ 4
	infix: 1 + 2 * 3 ^ 4
	postfix: 1  2  3  4 ^  *  +
	163.000
	2 ^ 5 - 1
	infix: 2 ^ 5 - 1
	postfix: 2  5  ^  1 -
	31.000
	q

Notes, suggestions, warnings, and additional requirements:

You should develop this program piecemeal, by handling the simplest cases first. Here is an example progression (milestones):
1. First work on handling user input. The program should let the user type in expressions until terminating with a leading 'q'. Your program at this point should just output the string the user has just entered.
2. Next, work on an evaluation function which will process a postfix input string, e.g., postfix: 2 4 * 3 + 11.000 or postfix: 4 3 2 * + 10.000
3. Then, work on converting an infix string into a postfix expression, concentrating for now on the simpler operators *, /, +, -, e.g., infix: 2 * 4 + 3 postfix: 2 4 * 3 + infix: 4 + 3 * 2 postfix: 4 3 2 * + Your code should be able to pass the resulting postfix expression to your evaluation routine, which should produce the correct solution.
4. Next, tackle the more complicated ^ exponentiation expression. 2 ^ 3 ^ 3 infix: 2 ^ 3 ^ 3 postfix: 2 3 3 ^ ^ 134217728.000
5. Then, work on providing a way to handle expressions nested in ()'s, e.g., 2 * (3 + 4) infix: 2 * (3 + 4) postfix: 2 3 4 + * 14.000 (3 + 4) * 2 infix: (3 + 4) * 2 postfix: 3 4 + 2 * 14.000

What to hand in:

``Professional-quality'' code distribution file, including student identification in a README plain text file: Course Id--Section No.
Name:
SS No:
Assignment No.

Electronic submission of source code: provide a self-contained, gzipped .tar of your project 1 directory, complete with a Makefile and README files. See the tar'ing instructions web page for further info on creating the tar file.
Your code MUST compile and run on a SUN machine.