C++ Primer课后练习9.52

#include<iostream>
#include<stack>
#include<fstream>
#include<string>
using namespace std;
int main(void)
{
int biaozhi = 0;
ifstream is("file1.txt");
ofstream os("file2.txt");
stack<char> stack1;
string word;
string line;

while (getline(is,line))
{
for (auto s : line)
{
stack1.push(s);
if (s == '(')
++biaozhi;
if (s == ')' && biaozhi)
{
while (stack1.top()!= '(')
{
stack1.pop();

}
stack1.pop();
--biaozhi;
stack1.push('@');   //用@代替原括号内内容
}
}
}
string s1;
while (!stack1.empty())
{
s1.insert(s1.begin(), stack1.top());
stack1.pop();
}
for (auto s : s1)
os << s;
return 0;
}

file1.txt
what the heck are(sdfkj(df)fsskfj)(hahas) you  doing now! man!
I just want to (slkjfjdhjgdgjkjkd(sdfudsuigyuidfyigyduifhgudhuighuidhufduhugfhuifgh)) kiss you,lady(sdfsfsg)!

file2.txt
what the heck are@@ you  doing now! man!I just want to @ kiss you,lady@!