11. Counter, Arithmetic Mean and Division by Zero
Keywords Are Reserved
We have stumbled upon many words that have
special meaning in the C++ language, such as double, int, for, if, else, using, namespace.
You can probably notice that your source code editor is displaying those words
in a different color. These words are recognized by the C++ compiler as having
a preset and special meaning in the language, which is why they are called the keywords. It is not possible to introduce a name that
would be the same as a keyword. It is thus said that the keywords are reserved
in the C++ language.
Other words that you have encountered, like
cin, cout, endl, main, vector are not keywords. These words are names, more precisely
identifiers, created by other features of the language.