Difference bitween # and ##

[rontdu]

Anybody can tell me the difference between single # and double ## in c or c++ programming. I know the name of the ## is pasting preprocessor operator. But what's the use of this operator?

[daman371]

# is used for preprocessor directives but is also used in macros with ##. see http://msdn2.microsoft.com/en-us/library/09dwwt6y(vs.71).aspx.