Re: Returning Char array/pointer? Continuing of thread I am confused with these concepts.

From:
rockdale <rockdale.green@gmail.com>
Newsgroups:
microsoft.public.vc.language
Date:
Mon, 11 Feb 2008 13:12:34 -0800 (PST)
Message-ID:
<213ed321-db94-4c21-8e7f-25e2642098b6@p69g2000hsa.googlegroups.com>
This is my function using std::string

std::string ReadFile2String(char const* aSrcFile){
    ifstream in;
    std::string strRtn;
    long lngFileSize = 0;

    in.open(aSrcFile, ios::in| ios::binary | ios::ate);
    if(in.is_open()||in.bad())
    {
        lngFileSize = in.tellg();
    }else{
        throw exception("could not open input file"); // could not open in
file
        return NULL;
    }

    char* chrTmp = new char[lngFileSize];
    in.seekg(0,ios::beg);
    in.read(chrTmp, lngFileSize);

    strRtn = chrTmp; ???????
    return strRtn;

}

use the function overrides that accept a length. what is the function?


My function does not return the correct result, the strRtn contains
extra bytes like AB AB AB FE FE FE....

On Feb 11, 3:39 pm, "Ben Voigt [C++ MVP]" <r...@nospam.nospam> wrote:

I am working on
std:string ReadFileToString( const char* fileName)
My concern is my file is an encrypted file and I open it as binary,
what if it happen contains '\0' in the middle, did the string get
truncated.


std::string stores the length separately instead of depending on a
terminator, to store embedded nulls you just have to use the function
overrides that accept a length.

However std::vector<char> is probably better in your case since you are
wanting to treat the data more like an array than a string. std::vector=

 you

can directly use as the buffer for file I/O, with std::string you are
expected to pass in a buffer already containing the data (either to the
constructor or to the append member function).

Again, thanks- Hide quoted text -


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