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file_to_memory.cpp
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file_to_memory.cpp
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/*
http://stackoverflow.com/questions/539537/how-to-write-to-a-memory-buffer-with-a-file
*/
#include <cassert>
#include <cstring>
#include <fstream>
#include <iostream>
#include <ostream>
#include <sstream>
template <typename char_type>
struct ostreambuf : public std::basic_streambuf<char_type, std::char_traits<char_type> > {
ostreambuf(char_type* buffer, std::streamsize bufferLength) {
this->setp(buffer, buffer + bufferLength);
}
};
void write(std::ostream& os) {
os << "abc";
}
int main() {
/* To memory, in our own externally supplied buffer. */
{
char c[3];
ostreambuf<char> buf(c, sizeof(c));
std::ostream s(&buf);
write(s);
assert(memcmp(c, "abc", sizeof(c)) == 0);
}
/* To memory, but in a hidden buffer. */
{
std::stringstream s;
write(s);
assert(s.str() == "abc");
}
/* To file. */
{
std::ofstream s("a.tmp");
write(s);
s.close();
}
/* I think this is implementation defined.
* pusetbuf calls basic_filebuf::setbuf(). */
{
char c[3];
std::ofstream s;
s.rdbuf()->pubsetbuf(c, sizeof c);
write(s);
s.close();
//assert(memcmp(c, "abc", sizeof(c)) == 0);
}
}