如何在C ++中的混合字符串整数行中提取特定整数

Question

I am reading a text file in c++, this is example of some lines in it:

remove 1 2 cost 13.4

How could I disregard all things except two integers after remove, "1" and "2" and put them in two integer variable?

my incomplete code:

ifstream file("input.txt");
string line;
int a, b;

if(file.is_open())
{
   while (!file.eof())
   {
      getline (file, line);
      istringstream iss(line);
      if (line.find("remove") != string::npos)
      {     

          iss >> a >> b;      // this obviously does not work, not sure how to
                              // write the code here
      }
   }

}

Answer 1

Here are a few options:

1. Use the stringstream created for the line to find the remove token and parse the next two integers. In other words, replace this:

    if (line.find("remove") != string::npos) { iss >> a >> b; // this obviously does not work, not sure how to // write the code here } 

   with this:

    string token; iss >> token; if (token == "remove") { iss >> a >> b; } 

2. Create a stringstream for the rest of the line ( 6 is the length of the "remove" token).

    string::size_type pos = line.find("remove"); if (pos != string::npos) { istringstream iss(line.substr(pos + 6)); iss >> a >> b; } 

3. Call the seekg method on the line stringstream to set the input position indicator of the stream after the "remove" token.

    string::size_type pos = line.find("remove"); if (pos != string::npos) { iss.seekg(pos + 6); iss >> a >> b; }