C / C++ / MFC

dburns wrote:

Hi,

Suppose I have a method foo that takes a const char* param. I have a case where I can be more efficient if the caller passes in a "quoted literal string" vs the contents of some arbitrary buffer (because I don't have to copy the string data in the first case).

CPallini wrote:

IMHO, You completely miss the efficience target...

foo(const char * pBuffer)
{
  // perform a copy of the given buffer
  ...
  // call the copy-free member
  foo_without_copy(pCopiedBuffer);
}
foo_without_copy( const char * pBuffer)
{
...
}

CPallini wrote:

Or are you're talking about an internal copy done by you're class?

dburns wrote:

I need the compiler to differentiate, if it's possible. I doubt it is.

dburns wrote:

I'd rather the compiler did the work

dburns wrote:

..."quoted literal string" vs the contents of some arbitrary buffer (because I don't have to copy the string data in the first case).

dburns wrote:

char buff[100];
...
const char* p_buff = buff;
myclass.foo(p_buff)

DavidCrow wrote:

Why use p_buff when you can pass buff directly to the foo() method?

char buff[100];<br />
...<br />
StringClass s1(buff); // Works: will use the non-const constructor and will copy.<br />
const char* ptr = ...; // possibly points at some local temp buffer<br />
StringClass s2(ptr); // Can't distinguish between this case...<br />
StringClass s3("hello"); //... and this case