Reverse Polish Notation (RPN) using C++

rpn.cpp

/*
 * This code was compiled using g++-7 on Ubuntu 16.04LTS platform using following command
 * g++-7 -std=c++17 rpn.cpp
 * ./a.out
 */

#include <iostream>
#include <vector>
#include <boost/algorithm/string.hpp>
#include <boost/lexical_cast.hpp>
#include <cctype>

inline bool is_punct(const std::string &str)
{
    if(str.length() != 1) return false;
    return ispunct(boost::lexical_cast<char>(str));
}

int main()
{
    std::string eval;
    getline(std::cin, eval);
    std::vector<std::string> tokens;

    boost::split(tokens, eval, [](char c){return c == ' ';});

    std::vector<int> temps;
    for(const auto &t: tokens){
        if(is_punct(t)){
            char op = boost::lexical_cast<char>(t);
            int n1 = temps.back();
            temps.pop_back();
            int n2 = temps.back();
            temps.pop_back();
            switch(op){
                case '+': temps.push_back(n2 + n1); break;
                case '-': temps.push_back(n2 - n1); break;
                case '*': temps.push_back(n2 * n1); break;
                case '/': temps.push_back(n2 / n1); break;
            }
        } else {
            temps.push_back(boost::lexical_cast<int>(t));
        }
    }

    std::cout << temps.back() << '\n';

    return 0;
}