If the /Ss compiler option (Intel) is in effect when you compile a C program, double slashes (//) also specify the beginning of a comment. The comment ends at the next new line character. C++ also permits double-slash comments as part of the language definition.
A C++ comment can span more than one physical source line if it is joined into one logical source line with line-continuation (\) characters. The backslash character can also be represented by a trigraph.