Trouble with garbage chars in visual c++ file reading - visual-c++

Question

I am trying to read a text file using the following code:
void function readfile(char *inputfile) {
istream is;
int filesize = 0;
is.open(inputfile);
if (!is.is_open()) {
return;
}
is.seekg(0, ios::end);
filesize = (int)is.tellg();
is.seekg(0, ios::beg);
char *buf = new char[filesize];
is.read(buf, filesize);
is.close();
cout << buf << endl;
delete[] buf;
return;
}
While in g++ (mac / macports) it works correctly (getting all contents into a dynamic allocated char* array), in Visual Studio C++ 2010, I get constant errors of this type: Debug assertion failed: (unsigned)(c+1) <= 256, file isctype.c.
The problem is that it opens the file but can't find a termination delimeter so when it reaches the eof it starts reading somewhere else (garbage characters). Using the cout << buf; I can see that the file is being read correctly in mac but in visual c++ it types more garbage chars. What is the problem here?

Answer 1

Make your buffer one larger and add the terminating nul yourself.

Answer 2

Let C++ standard library do the work for you:
void readfile(const char *inputfile) {
std::ifstream is(inputfile);
std::string buf(std::istreambuf_iterator<char>(is), {});
std::cout << buf << std::endl;
}
See, it's now also
exception safe
handles embedded NUL characters correctly
Note, of course you can use vector instead of string if you prefer (just change that one word)
Full demo: see it live on Coliru
#include <fstream>
#include <iostream>
#include <iterator>
void readfile(const char *inputfile) {
std::ifstream is(inputfile);
std::string buf(std::istreambuf_iterator<char>(is), {});
std::cout << buf << std::endl;
}
int main()
{
readfile("main.cpp");
}
Update For C++11 challenged compilers (and showing how to use a vector):
Also Live on Coliru
#include <fstream>
#include <iostream>
#include <iterator>
#include <vector>
void readfile(const char *inputfile) {
std::ifstream is(inputfile);
std::istreambuf_iterator<char> f(is), l;
std::vector<char> buf(f, l);
std::cout.write(buf.data(), buf.size());
}
int main()
{
readfile("main.cpp");
}