The most efficient, but not the C++ way would be:
FILE* f = fopen(filename, "r");
// Determine file size
fseek(f, 0, SEEK_END);
size_t size = ftell(f);
char* where = new char[size];
rewind(f);
fread(where, sizeof(char), size, f);
delete[] where;
#
EDIT - 2
Just tested the std::filebuf
variant also. Looks like it can be called the best C++ approach, even though it's not quite a C++ approach, but more a wrapper. Anyway, here is the chunk of code that works almost as fast as plain C does.
std::ifstream file(filename, std::ios::binary);
std::streambuf* raw_buffer = file.rdbuf();
char* block = new char[size];
raw_buffer->sgetn(block, size);
delete[] block;
I've done a quick benchmark here and the results are following. Test was done on reading a 65536K binary file with appropriate (std::ios:binary
and rb
) modes.
[==========] Running 3 tests from 1 test case.
[----------] Global test environment set-up.
[----------] 4 tests from IO
[ RUN ] IO.C_Kotti
[ OK ] IO.C_Kotti (78 ms)
[ RUN ] IO.CPP_Nikko
[ OK ] IO.CPP_Nikko (106 ms)
[ RUN ] IO.CPP_Beckmann
[ OK ] IO.CPP_Beckmann (1891 ms)
[ RUN ] IO.CPP_Neil
[ OK ] IO.CPP_Neil (234 ms)
[----------] 4 tests from IO (2309 ms total)
[----------] Global test environment tear-down
[==========] 4 tests from 1 test case ran. (2309 ms total)
[ PASSED ] 4 tests.