问c++如何删除/替换文件的最后一行？

EN

#include <fstream>
#include <string>
using namespace std;

int main() {
    ifstream fin("input.txt");
    ofstream fout("output.txt");

    
    while (!fin.eof()) {
        string buffer;
        getline(fin, buffer);
        
        if (fin.eof()) {
            fout << "text to replace last line";
        } else {
            fout << buffer << '\n';
        }
    }

    fin.close();
    fout.close();
}

#include <fstream>
#include <vector>
#include <string>
using namespace std;

int main() {
    // read
    ifstream fin("input.txt");
    vector<string> lines;
    
    while (!fin.eof()) {
        string buffer;
        getline(fin, buffer);
        lines.push_back(buffer + '\n');
    }
    fin.close();

    // modify
    lines[lines.size() - 1] = "text to replace last line";

    // write
    ofstream fout("output.txt");
    for (string line: lines) { // c++11 syntax
        fout << line;
    }
    fout.close();
}