C++ interactive command line prompt without waiting for a newline character

Is there a way to process command line input before seeing the newline character? I'm thinking of making a program that supports autocomplete (like the ones found in search engines or iOS keyboard).

To be more specific, my program will prompt for user input when started, and for each character input, I would like to output something BEFORE the newline character(or EOF) is input.

The following code snippet is what I have tried:

int main(){
    char ch; 
    while ( (ch = cin.get()) != cin.eof() )
    {       
        cout << ch << flush;
    }   
}

expected: for each character input, output that character.

actual: does not output anything UNTIL the program sees an eof.