Question

I would like to load the contents of a text file into a vector<char> (or into any char input iterator, if that is possible). Currently my code looks like this:

std::vector<char> vec;
std::ifstream file("test.txt");
assert(file.is_open());
while (!(file.eof() || file.fail())) {
    char buffer[100];
    file.read(buffer, 100);
    vec.insert(vec.end(), buffer, buffer + file.gcount());
}

I do not like the manual use of a buffer (Why 100 chars? Why not 200, or 25 or whatever?), or the large number of lines that this took. The code just seems very ugly and non-C++. Is there a more direct way of doing this?

Answer 1

Another approach, using rdbuf() to read the whole file to a std::stringstream first:

#include <fstream>
#include <sstream>
#include <vector>
#include <string>

// for check:
#include <algorithm>
#include <iterator>
#include <iostream>

int main() {
   std::ifstream file("test.cc");
   std::ostringstream ss;
   ss << file.rdbuf();
   const std::string& s = ss.str();
   std::vector<char> vec(s.begin(), s.end());

   // check:
   std::copy(vec.begin(), vec.end(), std::ostream_iterator<char>(std::cout));
}