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Buffers must be provided to called functions to retrieve complex information. From a logical point of view this information can be:
| • | A text string (Ansi or Unicode) |
| • | A simple structure with a fixed size |
| • | A structure with dynamically sized components, e.g. the image of a bitmap file |
| • | A nested structure with dynamic substructures |
| • | An array of strings, structures, interfaces, fake objects, ... or simple values |
| • | Just a chunk of memory to provide space for other parameters |
When handling buffers you will be confronted with the following values:
Before the call
| • | The address of the buffer) |
| • | The size of the buffer in bytes |
| • | The size of the buffer in number of entries in case of arrays |
| • | Length information in case of a text string |
After the call
| • | Information if the call succeeded, in case it didn't you must figure out if the buffer size was the problem |
| • | The size of the returned value in the buffer (after call) |
| • | The number of valid entries returned in the buffer |
| • | Sometimes the size required to retrieve the requested information |
| • | Sometimes the size required to retrieve the next bit or all available information |
For the call
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