I want cin to read until '\n' but I cannot use getline

Question

I have a text file in the following format:

info
data1 data2
info
data1 data2 data3 data4...

The problem is: the count (and length) of the data may be very large and cause run-time problems when getline() is used. So I cannot read the entire line into a std::string. I tried the following:

for(int i=0; i<SOME_CONSTANT ; i++){
    string info, data;

    cin >> info;

    while(cin.peek() != '\n' && cin >> data){
         // do stuff with data
    }
}

However cin.peek() did not do the trick. The info is read into data in the while loop and program messes things up. How can I fix this?

Answer 1

You can try reading character by character.

char ch;
data = "";
cin >> std::noskipws;
while( cin >> ch && ch != '\n' ) {
  if ( ch == " " ) {
    // do stuff with data
    data = "";
    continue;
  }
  data += ch;
}
cin >> std::skipws;

Answer 2

Use std::istream::getline instead of std::getline. You can choose your buffer size and delimiter.