Re: memory leaks

From:
Richard Herring <junk@[127.0.0.1]>
Newsgroups:
comp.lang.c++
Date:
Mon, 25 Jan 2010 17:35:39 +0000
Message-ID:
<Vvdt2izrZdXLFweM@baesystems.com>
In message <4b5dcf0e$0$819$4fafbaef@reader5.news.tin.it>, Larry
<dontmewithme@got.it> writes

"Bo Persson" <bop@gmb.dk> ha scritto nel messaggio
news:7s60mgFd8jU1@mid.individual.net...


[aside: why is everyone posting low-level C code this week?]

So, if it is not a string you could try std::vector<unsigned char>
instead. That's a good type for a byte buffer.


That's what I have been looking for!


You're using strftime and printf("%s") on it. That looks like a string
to me.

Anyway now I have trouble with the following:

void getDateTime(char * szTime);


Can't you make this into a function that returns a std::string?

const int numbuff = 5;
const int buflen = 30;

struct Buffer
{
public:
vector<char> vChar;
unsigned int bufferLength;
unsigned int bytesRecorded;


What's the point of bufferLength and bytesRecorded now? vector does its
own housekeeping, so there's no need for you to.

Buffer() : bytesRecorded(0), bufferLength(0), vChar(NULL) { };


Lose that. vector's default constructor will work fine.

};

int main()
{
circular_buffer<Buffer> cb(numbuff);
circular_buffer<Buffer>::const_iterator it;


You declare these but never use them.

for(int i = 0; i<10; i++)
{


And you do this 10 times for no good reason. I think you've lost track
of the need for a circular buffer somewhere along the way ;-(

// Get time
char szTime[30];


Is that 30 the same as the "buflen" you declared earlier?
Why the Hungarian prefix?

getDateTime(szTime);

// Init Buff
Buffer buff;
ZeroMemory(&buff, sizeof(Buffer));


Don't do that. Buffer's constructor should do all you need to do to
initialise it.

buff.vChar.resize(buflen);


Don't do that. Assigning to the buffer will do all that's necessary.

buff.vChar = szTime;


buff.vChar.assign(szTime, szTime+strlen(szTime));

Better still, give Buffer a constructor with appropriate arguments which
initialises the buffer.

buff.bufferLength = buflen;
buff.bytesRecorded = buflen;


Redundant. Just use buff.vChar.size();

printf("%s\n", buff.vChar);


printf("%s\n", &buff.vChar[0]);

}

system("pause");
return EXIT_SUCCESS;
}

// getDateTime (Fri, 10 Oct 2008 14:41:59 GMT)
void getDateTime(char * szTime)
{
time_t rawtime = time(NULL);
struct tm timeinfo;
gmtime_s(&timeinfo, &rawtime);
strftime(szTime, 30, "%a, %d %b %Y %X GMT", &timeinfo);


Is that "30" the same as the "buflen" you declared earlier?

}

The code fails here: buff.vChar = szTime;


If you'd used string instead of vector<char> it would have worked ;-)
Because it's such a common operation, string (unlike vector) has an
assignment operator that takes a pointer to a C-style null-terminated
string.

???


Try "Accelerated C++".

thanks


--
Richard Herring

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