Are C standard library functions considered part of C programming language
The “C programming language“ is defined by a document that defines the syntax and the semantics of programs, and the C standard library. So both are part of the “C programming language”.
However, in CS the term “language” is used in a different way, as a set of strings. You can define a language based purely on the syntax In the C Standard document - that allows you to distinguish between strings that are formally in the language and those that are not, but you still have no clue what a program would do.
You can also incorporate some semantic rules, so that for example int a[-10] or int i = &quot;String&quot; are not considered to be part of the language.