Velocity Reviews

Velocity Reviews (http://www.velocityreviews.com/forums/index.php)
-   C++ (http://www.velocityreviews.com/forums/f39-c.html)
-   -   Base64 from file (http://www.velocityreviews.com/forums/t645329-base64-from-file.html)

Chunekit Pong 11-20-2008 08:26 AM

Base64 from file
 
What's the problem with this code?

the purpose is to convert binary file into a Base64 string

I seem to have problem in the following line
BYTE const* pbBinary = &bytes[0];
int size = sizeof(pbBinary);

=================
typedef unsigned char BYTE;
std::ifstream file1("c:/test2.png");

// read from test2.png into BYTE array
std::vector<BYTE> bytes(
(std::istreambuf_iterator<char>(file1))
, (std::istreambuf_iterator<char>())
);
if(bytes.empty())
; // no bytes have been read

BYTE const* pbBinary = &bytes[0];
int size = sizeof(pbBinary);

unsigned long ulEncLen = 0;
char *pEncOut = NULL;

BOOL fRet = ::CryptBinaryToString( pbBinary, size,
CRYPT_STRING_BASE64, pEncOut, &ulEncLen );
====================
BOOL WINAPI CryptBinaryToString(
__in const BYTE *pbBinary,
__in DWORD cbBinary,
__in DWORD dwFlags,
__out_opt LPTSTR pszString,
__inout DWORD *pcchString
);

anon 11-20-2008 09:13 AM

Re: Base64 from file
 
Chunekit Pong wrote:
> What's the problem with this code?
>


It doesn't compile

> the purpose is to convert binary file into a Base64 string
>


What's Base64 string?

> I seem to have problem in the following line
> BYTE const* pbBinary = &bytes[0];
> int size = sizeof(pbBinary);
>


Most likely you will get 4 (depends on the platform you use)

> =================
> typedef unsigned char BYTE;
> std::ifstream file1("c:/test2.png");
>
> // read from test2.png into BYTE array
> std::vector<BYTE> bytes(
> (std::istreambuf_iterator<char>(file1))
> , (std::istreambuf_iterator<char>())
> );


Is this working?

> if(bytes.empty())
> ; // no bytes have been read
>
> BYTE const* pbBinary = &bytes[0];
> int size = sizeof(pbBinary);
>


I would do this:
const int size = bytes.size();

Chunekit Pong 11-20-2008 09:28 AM

Re: Base64 from file
 
On Thu, 20 Nov 2008 10:13:34 +0100, anon <anon@no.invalid> wrote:

>Chunekit Pong wrote:
>> What's the problem with this code?
>>

>
>It doesn't compile
>
>> the purpose is to convert binary file into a Base64 string
>>

>
>What's Base64 string?
>
>> I seem to have problem in the following line
>> BYTE const* pbBinary = &bytes[0];
>> int size = sizeof(pbBinary);
>>

>
>Most likely you will get 4 (depends on the platform you use)
>
>> =================
>> typedef unsigned char BYTE;
>> std::ifstream file1("c:/test2.png");
>>
>> // read from test2.png into BYTE array
>> std::vector<BYTE> bytes(
>> (std::istreambuf_iterator<char>(file1))
>> , (std::istreambuf_iterator<char>())
>> );

>
>Is this working?
>
>> if(bytes.empty())
>> ; // no bytes have been read
>>
>> BYTE const* pbBinary = &bytes[0];
>> int size = sizeof(pbBinary);
>>

>
>I would do this:
>const int size = bytes.size();


the full C++ file is like this - should compile
http://www.oniva.com/upload/1356/c3.cpp

Chunekit Pong 11-20-2008 10:17 AM

Re: Base64 from file
 
On Thu, 20 Nov 2008 10:13:34 +0100, anon <anon@no.invalid> wrote:

>Chunekit Pong wrote:
>> What's the problem with this code?
>>

>
>It doesn't compile
>
>> the purpose is to convert binary file into a Base64 string
>>

>
>What's Base64 string?
>
>> I seem to have problem in the following line
>> BYTE const* pbBinary = &bytes[0];
>> int size = sizeof(pbBinary);
>>

>
>Most likely you will get 4 (depends on the platform you use)
>
>> =================
>> typedef unsigned char BYTE;
>> std::ifstream file1("c:/test2.png");
>>
>> // read from test2.png into BYTE array
>> std::vector<BYTE> bytes(
>> (std::istreambuf_iterator<char>(file1))
>> , (std::istreambuf_iterator<char>())
>> );

>
>Is this working?
>
>> if(bytes.empty())
>> ; // no bytes have been read
>>
>> BYTE const* pbBinary = &bytes[0];
>> int size = sizeof(pbBinary);
>>

>
>I would do this:
>const int size = bytes.size();


I used the bytes.size();

but i found that - pEncOut - is not holding any string after calling
CryptBinaryToString function, when I debug it says bad Prt something.

After calling the function CryptBinaryToString - pEncOut shoul have
the Base64 string generated.

===================
char *pEncOut = NULL;

BOOL fRet = ::CryptBinaryToString( pbBinary, size,
CRYPT_STRING_BASE64, pEncOut, &ulEncLen );

anon 11-20-2008 11:26 AM

Re: Base64 from file
 
Chunekit Pong wrote:
> On Thu, 20 Nov 2008 10:13:34 +0100, anon <anon@no.invalid> wrote:
>
>> Chunekit Pong wrote:
>>> What's the problem with this code?
>>>

>> It doesn't compile
>>
>>> the purpose is to convert binary file into a Base64 string
>>>

>> What's Base64 string?
>>
>>> I seem to have problem in the following line
>>> BYTE const* pbBinary = &bytes[0];
>>> int size = sizeof(pbBinary);
>>>

>> Most likely you will get 4 (depends on the platform you use)
>>
>>> =================
>>> typedef unsigned char BYTE;
>>> std::ifstream file1("c:/test2.png");
>>>
>>> // read from test2.png into BYTE array
>>> std::vector<BYTE> bytes(
>>> (std::istreambuf_iterator<char>(file1))
>>> , (std::istreambuf_iterator<char>())
>>> );

>> Is this working?
>>
>>> if(bytes.empty())
>>> ; // no bytes have been read
>>>
>>> BYTE const* pbBinary = &bytes[0];
>>> int size = sizeof(pbBinary);
>>>

>> I would do this:
>> const int size = bytes.size();

>
> the full C++ file is like this - should compile
> http://www.oniva.com/upload/1356/c3.cpp


To open a file for binary read, you need to create ifstream object like
this:
std::ifstream file1( "c:/test2.png",
std::ios_base::binary |
std::ios_base::in );

Are you sure CryptBinaryToString works fine?

Thomas J. Gritzan 11-20-2008 01:18 PM

Re: Base64 from file
 
Chunekit Pong schrieb:
>>> =================
>>> typedef unsigned char BYTE;
>>> std::ifstream file1("c:/test2.png");
>>>
>>> // read from test2.png into BYTE array
>>> std::vector<BYTE> bytes(
>>> (std::istreambuf_iterator<char>(file1))
>>> , (std::istreambuf_iterator<char>())
>>> );

>> Is this working?
>>
>>> if(bytes.empty())
>>> ; // no bytes have been read
>>>
>>> BYTE const* pbBinary = &bytes[0];
>>> int size = sizeof(pbBinary);
>>>

>> I would do this:
>> const int size = bytes.size();

>
> I used the bytes.size();
>
> but i found that - pEncOut - is not holding any string after calling
> CryptBinaryToString function, when I debug it says bad Prt something.
>
> After calling the function CryptBinaryToString - pEncOut shoul have
> the Base64 string generated.
>
> ===================
> char *pEncOut = NULL;
>
> BOOL fRet = ::CryptBinaryToString( pbBinary, size,
> CRYPT_STRING_BASE64, pEncOut, &ulEncLen );


Of course it doesn't work. pEncOut is set to NULL. It won't magically
change to something else.

You would have to set pEncOut to some buffer and maybe ulEncLen to the
size of this buffer. Check out the documentation of this
CryptBinaryToString function.

--
Thomas


All times are GMT. The time now is 09:17 PM.

Powered by vBulletin®. Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO ©2010, Crawlability, Inc.