使用（FILE *）读取大型文本文件后发生垃圾

Question

I have a sample program written in C/C++, which reads a text file into memory. While trying to parse this file (not part of this sample), I came across lots of garbage near end of file. Investigating this I found there is some problem while reading large files into memory; this problem does not happen with small sized text files. Here is my code:

#include <conio.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

using namespace std;

char* readFile_(char* fname)
{
    char* rv=NULL;
    int bytes=0;
    FILE* pfile = NULL;
    pfile = fopen( fname, "r" );
    if ( pfile )
    {
        fseek(pfile, 0, SEEK_END);
        bytes = ftell(pfile);
        fseek(pfile, 0, SEEK_SET);
        rv = new char[bytes+1];
        memset(rv,0,bytes+1);
        fread( rv, bytes, 1, pfile );
        fclose(pfile);
    }
    return rv;
}

int main(int argc, char **argv)
{
    char* filebuffer = NULL;
    filebuffer = readFile_( "mv2.txt" );

    FILE* pfile = fopen("op.txt", "w");
    int len = strlen(filebuffer);
    fwrite( filebuffer, len, 1, pfile );
    fclose(pfile);

    delete[] filebuffer;
    return 0;
}

For reference, files are hosted here:

mv2.txt file: https://gist.github.com/anonymous/bb101393729d3ada944f
op.txt file: https://gist.github.com/anonymous/93595c83ad62e40d0f0a

Can anyone highlight what seems to be the problem?

Edit: I am using Windows (Windows 7 OS)

Edit 2: Thanks everyone for helping me find the problem, here is the updated code based on few of your feedbacks that seems to solve my problem even for some very large text files:

#include <conio.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

using namespace std;

char* readFile_(char* fname)
{
    char* rv=NULL;
    long bytes=0;
    FILE* pfile = NULL;
    pfile = fopen( fname, "rb" );
    if ( pfile )
    {
        fseek(pfile, 0, SEEK_END);
        bytes = ftell(pfile);
        fseek(pfile, 0, SEEK_SET);
        rv = new char[bytes+1];
        memset(rv,0,bytes+1);
        fread( rv, bytes, 1, pfile );
        fclose(pfile);
    }
    return rv;
}

int main(int argc, char **argv)
{
    char* filebuffer = NULL;
    filebuffer = readFile_( "mv2.txt" );

    FILE* pfile = fopen("op.txt", "wb");
    int len = strlen(filebuffer);
    fwrite( filebuffer, len, 1, pfile );
    fclose(pfile);

    delete[] filebuffer;
    return 0;
}

Answer 1

By including conio.h, I can make the assumption you are on Windows. In Windows, you will encounter problems in situations like this without using binary mode reads. I would try opening the file with "rb" as the mode.

FILE* pfile = NULL;
pfile = fopen( fname, "rb" );