Description

Stack Based Calculator
Value: 10%
Aims:
• Familiarity with C++ Containers
• File and string processing
Token Description Console
Output
x.y A double (where x and y are numbers). All doubles will have decimal places. e.g., 2.1
x An integer (where x is a number).
add Removes two numbers from the stack and calculates their sum. The sum is pushed back onto the stack. x + y = z
sub Removes two numbers from the stack and subtracts the second number removed from the first. The result is pushed back onto the stack. x – y = z
mult Removes two numbers from the stack and multiplies their product. The result is pushed back onto the stack. x * y = z
div Removes two numbers from the stack and divides the first by the second. The result is pushed back onto the stack. x / y = z
sqrt Removes the top of the stack and calculates the sqrt of this number. Pushes the result back onto the stack. sqrt y = z
pop Removes the top of the stack.
reverse Removes the top of the stack. The ordering of the next n (the number that was at the top of the stack) elements are reversed on the stack.
repeat Removes the top of the stack. Numbers and commands continue to be read from the file but not acted on until an endrepeat command.
endrepeat Processes the numbers and commands that were read from the input file but stored from the start of the repeat command. These numbers and commands are repeated n times (where n is the number that was at the top of the stack when the repeat command was given).
Sample input:
10 20 sub
4 3 add
2 mult
16.0 2 repeat sqrt endrepeat pop 2.0 mult
3 repeat
2 2 reverse div 3 mult endrepeat
Sample output:
20 – 10 = 10
3 + 4 = 7 2 * 7 = 14 sqrt 16.000 = 4.000 sqrt 4.000 = 2.000
2.000 * 14 = 28.000
28.000 / 2 = 14.000
3 * 14.000 = 42.000
42.000 / 2 = 21.000
3 * 21.000 = 63.000
63.000 / 2 = 31.500
3 * 31.500 = 94.500 Getting started:
The following program will allow you to read a file from the command line and sets up the formatting for printing doubles to three decimal places.
#include <iostream>
#include <fstream> #include <iomanip>

int main(int argc, char* argv[]) {

// setup the print out format for the precision required. std::cout.setf(std::ios::fixed,std::ios::floatfield); std::cout.precision(3);

// open the file for reading std::ifstream in; in.open(argv[1]);

// string to be read into std::string s;

// read the file while we have input.
while (in >> s) {

}
in.close();
}
Tips:
• Use C++! Do not use C-style printfs, unions, macros or arrays.
• Use the C++ STL – you shouldn’t build your own container classes or use other libraries (e.g., boost).
• To detect if a string is a double look for a ‘.’ in the token, e.g.,
s.find(‘.’) != std::string::npos
• To detect if a string is a number look for a number in the first position of the token, e.g., isdigit(s[0])
• To convert a string to an int or a double use std::stoi(s) or std::stod(s).
#include <cmath>
• Carefully consider when you need to promote an int to a double. Any command that only uses ints should return an int result, only commands that mix ints and doubles should result in a double.
• The reference solution is 250 lines including comments.
• All testing input will be valid and computable (e.g., no ‘-1 sqrt’) however you should be able to handle or ignore bad input.
• This assignment should be relatively easy, mixing ints and doubles is the only difficult bit.
• All your code should be placed in one C++ source file, you don’t need header or makefiles.
• Make sure your code reads a file specified in argv[1] and outputs using std::cout
Testing
Place all your code in a file called calculator.cpp
Ensure it compiles on the CSE machines under the following command:
g++ -std=c++14 -Wall -Werror -O2 -o calculator calculator.cpp To run your code type:
./calculator input.txt
You should create your own input files to test the full functionality of your code against the specifications.
Marking
Your submission will be given a mark out of 10 with 7 an automarked performance component for output correctness and 3 manually marked component for code style and quality.
As this is a third-year course we expect that your code will be well formatted, documented and structured. We also expect that you will use standard formatting and naming conventions.
Note, if you write in C or use C types (e.g. union) or #define macros you will lose performance marks as well as style marks.
A number of test cases will be used to mark your solution. To pass a test case, your solution must produce exactly the same output as the reference solution. The results from both will be compared by using the linux tool diff.
Submission Instructions
Copy your code to your CSE account and make sure it compiles without any errors or warnings. Then run your test cases. If all is well then submit using the command:
give cs6771 ass1 calculator.cpp
Acknowledgement