Go: package main

import (
	"bufio"
	"fmt"
	"go/token"
	"go/types"
	"os"
	"strconv"
	"strings"
)

func main() {
	stdin := bufio.NewScanner(os.Stdin)
	stdin.Scan()
	n, _ := strconv.Atoi(stdin.Text())
	for i := 0; i < n; i++ {
		stdin.Scan()
		exp := strings.TrimRight(stdin.Text(), "=")
		res, _ := types.Eval(token.NewFileSet(), nil, token.NoPos, exp)
		fmt.Println(res.Value)
	}
}

C++: #include <bits/stdc++.h>
#define ll long long
#define INF 1000000005
#define MOD 1000000007
#define EPS 1e-10
#define rep(i,n) for(int i=0;i<(int)(n);++i)
#define rrep(i,n) for(int i=(int)(n)-1;i>=0;--i)
#define srep(i,s,t) for(int i=(int)(s);i<(int)(t);++i)
#define each(a,b) for(const auto& (a): (b))
#define all(v) (v).begin(),(v).end()
#define len(v) (int)(v).size()
#define zip(v) sort(all(v)),v.erase(unique(all(v)),v.end())
#define cmx(x,y) x=max(x,y)
#define cmn(x,y) x=min(x,y)
#define fi first
#define se second
#define pb push_back
#define show(x) cout<<#x<<" = "<<(x)<<endl
#define sar(a,n) {cout<<#a<<":";rep(pachico,n)cout<<" "<<a[pachico];cout<<endl;}

using namespace std;

template<typename S,typename T>auto&operator<<(ostream&o,pair<S,T>p){return o<<"{"<<p.fi<<","<<p.se<<"}";}
template<typename T>auto&operator<<(ostream&o,set<T>s){for(auto&e:s)o<<e<<" ";return o;}
template<typename S,typename T,typename U>
auto&operator<<(ostream&o,priority_queue<S,T,U>q){while(!q.empty())o<<q.top()<<" ",q.pop();return o;}
template<typename K,typename T>auto&operator<<(ostream&o,map<K,T>&m){for(auto&e:m)o<<e<<" ";return o;}
template<typename T>auto&operator<<(ostream&o,vector<T>v){for(auto&e:v)o<<e<<" ";return o;}
void ashow(){cout<<endl;}template<typename T,typename...A>void ashow(T t,A...a){cout<<t<<" ";ashow(a...);}
template<typename S,typename T,typename U>
struct TRI{S fi;T se;U th;TRI(){}TRI(S f,T s,U t):fi(f),se(s),th(t){}
bool operator<(const TRI&_)const{return(fi==_.fi)?((se==_.se)?(th<_.th):(se<_.se)):(fi<_.fi);}};
template<typename S,typename T,typename U>
auto&operator<<(ostream&o,TRI<S,T,U>&t){return o<<"{"<<t.fi<<","<<t.se<<","<<t.th<<"}";}

typedef pair<int, int> P;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<double> vd;
typedef vector<P> vp;
typedef vector<string> vs;

const int MAX_N = 100005;

int dfs1(int& pos, const string& s);
int dfs2(int& pos, const string& s);

int dfs3(int& pos, const string& s){
    if(isdigit(s[pos])){
        int res = 0;
        while(isdigit(s[pos])){
            res = res * 10 + (s[pos++] - '0');
        }
        return res;
    }
    pos++;
    const int res = dfs1(pos, s);
    pos++;
    return res;
}

// m, d
int dfs2(int& pos, const string& s){
    int res = dfs3(pos, s);
    while(pos < (int)s.size()){
        if(s[pos] == '*'){
            ++pos, res *= dfs3(pos, s);
        }else if(s[pos] == '/'){
            ++pos, res /= dfs3(pos, s);
        }else break;
    }
    return res;
}

// a, s
int dfs1(int& pos, const string& s){
    int res = dfs2(pos, s);
    while(pos < (int)s.size()){
        if(s[pos] == '+'){
            ++pos, res += dfs2(pos, s);
        }else if(s[pos] == '-'){
            ++pos, res -= dfs2(pos, s);
        }else break;
    }
    return res;
}

int parse(const string& s){
    int pos = 0;
    return dfs1(pos, s);
}

int main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    int t;
    cin >> t;
    string s;
    rep(i,t){
        cin >> s;
        cout << parse(s) << "\n";
    }
    return  0;
}

C++: #include <iostream>
#include <stack>
#include <map>
#include <string>
#include <cctype>
using namespace std;

map<char,int> order;
string S; size_t cur=0;
stack<int> num,rnum;
stack<char> op,rop;

int digit(){
	int n=S[cur++]-'0';
	return n;
}

int number(){
	int n=digit();
	while(isdigit(S[cur]))
		n=n*10+digit();
	return n;
}

void calc(){
	int b=num.top();num.pop();
	int a=num.top();num.pop();
	char o=op.top();op.pop();
	int c;
	switch(o){
		case '+' :
			c=a+b;
			break;
		case '-' :
			c=a-b;
			break;
		case '*' :
			c=a*b;
			break;
		case '/' :
			c=a/b;
			break;
		default :
			break;
	}
	num.push(c);
	return ;
}

void calc2(){
	int a=rnum.top();rnum.pop();
	int b=rnum.top();rnum.pop();
	char o=rop.top();rop.pop();
	int c;
	switch(o){
		case '+' :
			c=a+b;
			break;
		case '-' :
			c=a-b;
			break;
		case '*' :
			c=a*b;
			break;
		case '/' :
			c=a/b;
			break;
		default :
			break;
	}
	rnum.push(c);
	return ;
}

int exp(){
	cur =0;
	int smax=S.size();
	while(cur < smax-1){
		//cout << cur << endl;
		if(isdigit(S[cur])){
			int a=number();
			num.push(a);
		}else if(!op.empty()&&op.top()!='('&&op.top()!=')'&& order[S[cur]] > order[op.top()]){ //計算順序については改善の余地あり (　は最小に
			calc();
			op.push(S[cur++]);
		}else if(S[cur] == ')' ){
			if(!op.empty()&&op.top()!='(')
				calc();
			rnum.push(num.top());num.pop();
 			while(!op.empty()&&op.top()!='('){
				rop.push(op.top());op.pop();
				rnum.push(num.top());num.pop();
			}
			while(!rop.empty())
				calc2();
			num.push(rnum.top());rnum.pop();
			//cout << num.top() << endl;
			op.pop();cur++;
		}else{//ひとまず終了　演算記号のチェックも入れる
			//	cout << "come" << endl;
			op.push(S[cur++]);
		}
	}

	if(op.size()>=2){
		char op1,op2;
		op1=op.top();op.pop();op2=op.top();
		op.push(op1);
		if(order[op1]<order[op2])
			calc();
	}
	//cout << num.top() << endl;//
	//int tmp1=num.top();num.pop();
	//cout << num.top() << endl;//
	//int tmp2=num.top();num.pop();
	//cout << num.top() << endl;//
	//num.push(tmp2);
	//num.push(tmp1);

	rnum.push(num.top());num.pop();
	while(!op.empty()&&op.top()!='('){
		rop.push(op.top());op.pop();
		rnum.push(num.top());num.pop();
	}
	while(!rop.empty())
		calc2();
	num.push(rnum.top());rnum.pop();
	//cout<< " check "  << op.empty() << endl;
	int ans=num.top();
	num.pop();
	return ans;
}

int main(void){
	order['+']=2;
	order['-']=2;
	order['*']=1;
	order['/']=1;
	//cout << order['('] << endl;
	int n;
	cin >> n;
	while(n--){
		cin >> S;
		cout << exp() << endl;
	}
	return 0;
}

C++: #include<iostream>
#include<string>
#include<sstream>
using namespace std;

string s;

int conv_stoi(string str){
  stringstream ss(str);
  int n;
  ss >> n;
  return n;
}

int parse(int l, int r){
  int n = 0;
  for(int i=r-1;i>=l;i--){
    if(s[i] == ')') n++;
    if(s[i] == '(') n--;
    if(!n){
      if(s[i] == '+') return parse(l,i) + parse(i+1,r);
      if(s[i] == '-') return parse(l,i) - parse(i+1,r);
    }
  }
  for(int i=r-1;i>=l;i--){
    if(s[i] == ')') n++;
    if(s[i] == '(') n--;
    if(!n){
      if(s[i] == '*') return parse(l,i) * parse(i+1,r);
      if(s[i] == '/') return parse(l,i) / parse(i+1,r);
    }
  }

  if(s[l] == '(' && s[r-1] == ')') return parse(l+1,r-1);
  return conv_stoi(s.substr(l,r-l));
}

int main(){
  int n;
  cin >> n;
  while(n--){
    cin >> s;
    cout << parse(0,(int)s.size()-1) << endl;
  }
}