Why does a C comment like /* */ need '<'?

Question

My teams C-code guidelines write that it'd be better to place a '<' in a comment like shown below:

#define MAX_PACK_ITEM_NUM 50  /**<  max number of item */ 

I wonder, what is the real use of this '<' ?

Answer 1

It's a way for doxygen to generate documentation for members of a file/struct/union/class/enum. By using that marker, you can put comments after each member, leading to less clutter. You can read more about it here.

Answer 2

As others have replied, this is probably a comment that is meant for doxygen. When parsing comments, doxygen have some special rules:

• An ordinary comment starting with /* is ignored by doxygen.
• A comment starting with /** is treated as documentation of the next item after the comment in the source code.
• A comment starting with /**< is treated as documentation of the item immediately before the comment in the source code.

Documentation is mostly placed above the documented item, e.g. a function. But in some cases such as a #define it makes sense to put the documentation at the end of the line instead and in that case the /**< marker is needed.