Re: VC6 vs VC9

""Louis Solomon [SteelBytes]"" <louis@steelbytes.com> wrote in message news:C66C95C4B9354B6681CF7CC24F8F029B@steelbytes.local... > Hi, > > based on comments on http://windows.php.net/qa/ ... > > why is the VC9 build compiled to used the CRT as DLLs instead of static? > yet I gather the VC6 isn't? I'm sure they both dynamically link to the CRT. When an application uses numerous DLLs and they each dynamically load the CRT, the CRT code is loaded once and all application binaries share a single memory heap. This means memory can be malloc()ed in one DLL and free()d in another. A static link to the CRT would not allow this, and would mean a copy of the CRT code would exist in each DLL. (By 'not allow' I mean memory corruption and crashes. Unfortunately the code will compile and link without incident.) > > why can't the VC9 build be used with apache.org binaries? Apparently apache.org's binaries are compiled w/ VC6. Mixing dynamically-loaded CRT versions creates a similar situation as statically linking it: separate heaps, meaning cross-binary memory management will cause heap corruption. Just as insidious is the possible difference in object size between the two CRT versions. If DLL A assumes a certain object is, say, 8 bytes and DLL B assumes 16 bytes, disaster is virtually assured. -Evan