Not all keyboards provide all the symbols used for the logical operators, so the C++ Standard provides alternative representations, as shown in Table 6.3. The identifiers
not are C++ reserved words, meaning that you can’t use them as names for variables and so on. They are not considered keywords because they are alternative representations of existing language features. Incidentally, these are not reserved words in C, but a C program can use them as operators, provided that the program includes the
iso646.h header file. C++ does not require using a header file.
cctypeLibrary of Character Functions
C++ has inherited from C a handy package ...