Question

I am just hoping on getting some tips on how to get started on my assignment.
It reads as follows:

“Implement a program that behaves similarly to the ‘dc’ utility, which evaluates expressions in a postfix notation, and also supports additional computations using variables and macro strings. Feel free to experiment with the existing utility and consulting its manual pages.
The assignment will support only a subset of the complete utility:
— all numeric values will be integers, only using radix 10

— numbers may be assumed to be within the range of 32-bit signed numbers

— all register names will be alphanumeric (a subset of those dc allows)

— no command line options or arguments will be required

— only the following commands are are required (listed in the same order as the manual)
p n f + – * / % ^ c d r s l S L x > !> < !< = != q #

Some key differences between the assignment and the existing utility:
— all input will be through standard input only (but not necessarily keyboard)

— register stacks are initially not empty, but filled with infinite zeros

— the q command will exit the program, regardless of macro call nesting level

— additional spaces may appear between input tokens for legibility
(the space is not a command or a value or a register name)”

I honestly don’t know where to start… Any help is greatly appreciated, thanks guys.

Answer 1

As it is an assignment and you do not know where to start here are some hints:

• Start with reading the stdin and split it into tokens
• implement the stack to store operands and results
• implement a few operations like +,-,*,/
• make it all working
• then implement the missing features one by one