解析txt文件C++时忽略commemts

Question

I have a large text file and I am parsing using string stream. Text file looks like this

#####
##bjhbv
nvf
vbhjbj
vfjbvjf
*bj
*bvjbv
.
.
.
.
+FILE
data I want to parse from here to 
.
.
.
.
-FILE 
till here
#shv again comments
.
.

How can I parse only between +FILE to -FILE? I can parse inside off it, but i just want to ignore above and below comments. Please help me how to ignore whie reading or parsing from .txt file. Any leads will be appreciated.,

Answer 1

Something like this should do it:

{
  ifstream f_in(input_file_name);
  ofstream f_out(output_file_name);

  string line;
  // discard up to "+FILE"
  while (getline(f_in, line) && line != "+FILE");
  // copy up to "-FILE"
  while (getline(f_in, line) && line != "-FILE") f_out << line << endl;
}

The ifstream and ofstream will close their respective files upon leaving scope, which is why I showed them within {} .

Answer 2

As you see in the comments, you can discard above +FILE. you can use flag and condition method. Where use,

while(some_condition)
{
 //ignore comments
 if(!std::find("#")) 
 {
   continue;
 }
 bool flag=false;
 if(!std::find("+FILE")) 
 {
   flag=true;
 }
 if(!std::find("-FILE"))
 {
   flag=false;
 }
if(flag)
 {
  ..
  ..
  ..
 }
}

You can also use enum and array index method if you have different string names. If you dont want to use std::find, if you are parsing through getline ,then you can replace std::find to line.at(0) .