Question

// file.in
12
13

// main.cpp
fstream f("file.in", ios::in);
int n;
char c;
f >> n;
f.get(&c);

After extracting the number 12, what is the next character? Is it newline or ‘1’? If I call getline instread of get, do I get an empty line or ’13’?

Answer 1

It leaves the delimiter in the input buffer, so the next character you read will be a new-line. Note, however, that most extractors will skip white space (which includes new-line) before anything they extract, so unless you do call something like getline this won’t usually be visible.

Edit: to test on something like ideone, consider using a stringstream:

#include <sstream>
#include <iostream>

int main(){ 
    std::istringstream f("12\n13");
    int n;
    char c;
    f >> n;
    f.get(c); // get takes a reference, not a pointer. Don't take the address.

    std::cout << "'" << c << "'";
    return 0;
}

I wouldn’t expect to see a difference between a stringstream and an fstream in something like this.