shadowCODE is right, but just to add: for purposes of putting it "above the function", yes, you'll often see the multi-line comments like that above function declarations, to explain what they do, usually in a header file (the "interface") for multi-file projects.
Also, another little thing: if, for some reason, you need a large section of compile-able code to be cut-off, but these sections have /* */-style comments in them, you can use the preprocessor
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#if 0
//code
... /* other comments */
//code
#endif