std::ptr_fun explanation?

[eNergizer]

Here's a snippet of some code I have.

// Check if the line starts with //, the program then ignores it but
			// it does display it to console and results.txt
			// Also skips calculating blank lines
			if (find_if(buffer.begin(), buffer.end(), std::not1(std::ptr_fun< int, int > (std::isspace)) ) == buffer.end() ||
				(buffer.size() >= 2 && buffer[0] == '/' && buffer[1] == '/') )
				continue; // Make it jump back to the beginning 

I know std::ptr_fun makes an instance of std::isspace that works with std::not1, but I know how std::ptr_fun works with the arguments. I'm guessing the overloaded version of std::isspace with an argument of 2 ints is selected? Can someone clarify this function for me?

[Bazzy]

the isspace from cctype takes an int as parameter and returns an int. That's what the template arguments of ptr_fun are about
http://www.cplusplus.com/reference/std/functional/ptr_fun/
http://www.cplusplus.com/reference/clibrary/cctype/isspace/
http://www.cplusplus.com/reference/std/locale/isspace/