#include <csignal>
#include <fstream>

ofstream result_file(result_file_path);

result_file.seekp(-1, ios::end);
int size = result_file.tellp();
result_file.close();

FILE* file = fopen(result_file_path.c_str(), "ab+");
int a=fileno(file);
ftruncate(a,size);