thischar is of the datatype char which has no methods at all like classes can have.
thischar can only hold ONE character, so extracting a line from it is .... magic?
you should post your whole sketch to get better feedback as I cannot really see what you try to accomplish.
The getline() function has been around since the old System V days. C++ has overloaded the function so there are more flavors than before. Google has over 100,000 hits on it.