uint64_t getFileSize(istream& stream)
{
 uint64_t cur, ret;
 cur = stream.tellg();
 stream.seekg(0, ios::end);
 ret = stream.tellg();
 stream.seekg(cur, ios::beg);
 
 return ret;
}
 
ifstream readfile(readpath.c_str(), ios::binary|ios::in);
 
uint64_t fileSize = getFileSize(readfile);
char *buf = new char[fileSize];
readfile.read(buf, fileSize);
 
for(size_t i=0; i<fileSize; i++)
{
 /* Haces lo que quieras con buf[i] */
 outputfile.put(buf[i]);
}
 
delete[] buf;
 

#include<iostream>
#include<fstream>
 
using namespace std;
 
int main(){
	ofstream outputfile;
	outputfile.open("file1",ios::out);
	ifstream readfile;
	readfile.open("file2",ios::in);
 
 
	while(readfile.good()){
		char writebuffer=readfile.get();
 
		if(readfile.good())outputfile.put(writebuffer);
	}
	readfile.close();
	outputfile.close();
}

#include<iostream>
#include<fstream>
 
using namespace std;
 
int main(){
	ofstream outputfile;
	outputfile.open("file1",ios::out);
	ifstream readfile;
	readfile.open("file2",ios::in);
 
	char writebuffer;
	while(readfile.read(&writebuffer,1)){
		if(readfile.good())outputfile.write(&writebuffer,1);
	}
	readfile.close();
	outputfile.close();
}