In C++, there is a set of defined escape sequences to store special characters into a string.
You are actually lucky that \N
is not within this set, because then you wouldn't even get a compiler warning; the text of the warning could have made you learn about escape sequences (unfortunately, it didn't).
Because the \
is used to prefix an escape sequence, you cannot use it directly; it has to be escaped itself:
">\\N999999.99;_"
This compiles to a single >\N999999.99;_
in the output.