expr.cpp

#include <iostream>
#include <cstdlib>

using namespace std;

int main(int argc, char* argv[]){
    string in(argv[1]);
    long res=0;
    int pn = 0;
    for(auto i=in.begin(); i!=in.end(); ++i){
        if(*i == '+') {
            res += pn;
        }else if(*i == '*'){
            res += (*(++i)-'0')*pn;
            pn=0;
        }else{
            pn = *i-'0';
        }
    }
    res+=pn;
    cout << "= " << res << endl;
    return 0;
}