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Keywords and Identifiers

Character Set

Character set are the set of alphabets, letters and some special characters that are vail in C language.

Alphabets :

Uppercase : A B C .......................... X Y Z

Lowercase : a b c .......................... x y z

Digits :

0 1 2 3 4 5 6 7 8 9

Special character :

Special character in c language

Special character in c language
,	<		.	-	(	)	;	$	:	%	[	]	#	?
+	~	\	_	\|	/	*	!	^	"	{	}	&	'

White space character

Blank space, new line,horizontal tab, carriage return form feed.

Keywords :

Keywords are the reserved words used in programming. Each keywords has fixed meaning and that cannot be changed by user. For example:

int money

Here, int is a keyword that indicates, 'money' 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
continue	for	signed	void
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

All these keywords, their syntax and application will be discussed in their respective topics. However, if you want brief information about these keywords without going further visit page : Function of keywords

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 cash;
        int car;

Here, cash is a identifier which denotes a variable of type integer. Similarly, car is another identifier, which denotes another variable of type integer.

Rules for writing identifier

: 1.An identifier can be composed of letters (both uppercase and lowercase letters), digits and underscore '_' only.; 2.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.; 3.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.

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