Keywords:
Keywords are the reserved words used in programming. Each
keywords has fixed meaning and that can't be changed by user. For e.g: int book;
Here, int is a keyword that indicates, 'book' is of type
integer.
As, C programming is case sensitive, all keywords must be
written in lowercase. Here is the list of all keywords predefined by ANSI C.
Keywords in C Language:
auto double int struct
break else long switch
case enum register
typedef
char extern return
union
for signed void continue
do if static while
default goto sizeof
volatile
const float short
unsigned
Besides these keywords, there are some additional
keywords supported by Turbo C.
Additional Keywords for Borland C:
asm ,far, interrupt ,pascal ,near, huge, cdecl
Identifiers:
In C programming, identifiers are names given to C
entities, such as variables, functions, structures etc. Identifier are created
to give unique name to C entities to identify it during the execution of
program. For example:
int money;
int mango_tree;
Here, ‘money’ is a identifier which denotes a variable of
type integer. Similarly, ‘mango_tree’ is another identifier, which denotes
another variable of type integer.
Rules for writing identifier:
An identifier can be composed of letters (both uppercase
and lowercase letters), digits and underscore '_' only.
The first letter of identifier should be either a letter
or an underscore. But, it is discouraged to start an identifier name with an
underscore though it is legal. It is because, identifier that starts with
underscore can conflict with system names. In such cases, compiler will
complain about it. Some system names that start with underscore are _fileno,
_iob, _wfopen etc.
There is no rule for the length of an identifier.
However, the first 31 characters of an identifier are discriminated by the
compiler. So, the first 31 letters of two identifiers in a program should be
different.
Tips for Good Programming Practice :
Programmer can choose the name of identifier whatever
they want. However, if the programmer choose meaningful name for an identifier,
it will be easy to understand and work on, particularly in case of large
program.
