Elements of C Language

 

Elements of C Language

 

Let us discuss about elements of C language. The first one is Character Set. 

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The C Character Set

The basic programming elements like variables, constants, keywords, operators, expressions, statements etc. can be created using characters, numbers and special characters are commonly called character set in C Language. Which are as under-

Alphabets : a to z (lowercase letters)

A to Z (uppercase letters)

Digits: 0 1 2 3 4 5 6 7 8 9

Special Characters :    + – * / % = & | ^ ! # $ ~ { } [ ] ( ) ” ‘ , . < > > _ : ; \ (blank space)

When these above mentioned special characters are used in certain combination, resulting in some special meaning.  e.g ++ — << >> +=  -= *= /= %= |= != == [] () etc

Escape Sequence : \n \a \b \” \’ \\ \f \t \v etc.

The next elements of C Language is Identifiers

Identifiers

An identifier in c language is a name given to an element which is used to identify a variable, constant, function, array, structure or any other user-defined element

Rules to name an identifier

1)    The name must begin with either a letter or an underscore.

2)    It should not be much longer.

3)    Name can’t contain any special character other than ‘_’.

4)    It can have digits after first character or underscore.

5)    No blank space is allowed in an identifier name.

6)    Identifier name should be self explanatory. which means if you are writing an identifier for a student name then it can      be like, studentname, sname etc.

7)    There are some reserved words in C language which can’t be     used for user defined identifiers.

8)    C is case sensitive so ‘Name’ and ‘name’ are two different   identifiers.

Examples of some valid identifier names –

place, total_salary, Age,  _username, b2b, a12 etc

Examples of some invalid identifier names –

2nd, student name, default, name’s etc

The next elements of C Language is keywords

Keywords

C has 32 reserved words, which have special meaning in c. These words can’t be used to name any variable, constant or any other identifier.

auto	else	long	switch
break	enum	register	typedef
case	extern	return	union
char	float	short	unsigned
const	for	signed	void
continue	goto	sizeof	volatile
default	if	static	while
do	int	struct	double

These keywords will be discussed in details as we progress in c.

Next Elements of C Language is data types

Data Types in C Language

Data types of an object determine the set of values it can take and the operations that can be performed on it.

The types in C can be classified as follows −

1. Basic Data Types
2. Derived Data Types

Basic Data Types:

Basic data types are of 5 types as discussed below-

The following table provides the details of standard  char, integer and double date types with their storage sizes and value ranges −

S.No	Type of Data	Declarator	Typical Size	Range
1	Character Data Type	char	1 byte	-128 to 127
2	Integer Data	Int	2 bytes	-32768 to 32767
3	Real or Floating point data	Float	4 bytes	3.4×10-38to 3.4×1038 with 6 digits of percision
4	Double data type	Double	8 bytes	1.7×10-308 to 1.7×10308 with 10 digits of precision
5	Void	Void	–	–

To get the exact size of a type or a variable on a particular platform, you can use the sizeof operator.

Derived Data Types

Derived data types can be Pointers, Arrays, Structures, Unions and functions types.

Type Modifiers

Basic data types can be modified except void and float to accommodate to specific needs. So to accommodate the need a keyword precedes the basic data type to represent the storage requirements. This keyword is called Type Modifier.

Type	Storage size	Value range
char	1 byte	-128 to 127 or 0 to 255
unsigned char	1 byte	0 to 255
signed char	1 byte	-128 to 127
int	2 bytes	-32,768 to 32,767
unsigned int	2 bytes	0 to 65,535
short	2 bytes	-32,768 to 32,767
unsigned short	2 bytes	0 to 65,535
Long or long int	4 bytes	-2,14,74,83,648 to 2,14,74,83,647
unsigned long int	4 bytes	0 to 4,29,49,67,295
Long double	10 bytes	3.4×10-4932 to 1.1×104932

Next Elements of C Language is format specifiers

Format Specifiers

Format specifiers are used to specify the type of data a variable can take during input/output or read/write operations. The list of format specifiers is as under –

To Read or Write a	Format specifier
Signed char	%c
Signed decimal integer	%d
Unsigned decimal integer	%u
Unsigned octal integer	%o
Unsigned hexadecimal integer	%x
Floating pointing number	%f
Scientific floating point number	%e
Character String	%c
Long Integer	%ld
Double Precision Integer	%lf

Next Elements of C Language is constants

Constants

A constant is just a fixed value or a value found in an expression that a program may not change. A constant can be of any data type except void in C language. Constants are also called literals.

Constants don’t have memory locations but many compilers place string constants in the memory.

Types of constants in C Language-

1)    Numeric constants  

       Numeric constants are further divided into two types – integer constants and floating point constants

i) Integer Constants -Integer constants are the constants without fractional part. These can be

ii) Decimal Integers – Decimal numbers have 10 basic numbers from 0-9, e.g. 0,1,2,9 etc. It does not start with 0 unless the number itself is 0.

iii) Octal Integer – Octal numbers consists of numbers in the range of 0-7, starting with prefix 0 eg 0123,0456 etc. It always starts with 0.

iv) Hexadecimal Integers – These numbers have 16 basic numbers 0-9,a-f. and starts with 0x e.g. 0x199a and 0xaf42.

2) Floating Point numbers – These numbers contain decimal point or letter e or both. e.g. 3.14, 123.234e3

2) Character Constants 

When a single character is enclosed in single quotes then it is called character constant.

e.g. ‘A’,’a’, ‘.’ etc.

The numeric value of character constants is fixed and is as per ASCII (American Standard Code for Information Interchange) table, which is 97 for ‘a’ and 65 for ‘A’.

3) String Constants 

This is a sequence of zero or more characters enclosed in double quotes e.g. “abc”, “Ram”, “baby” etc. C compiler always terminates a string with an extra null byte (‘\0’) so storage space required for a string is always one more than the no. of characters.

“Ram” string contains 3 characters but it’s memory layout would be-

R

A

M

\0

Hence it would occupy 4 bytes of storage space.

4) Escape Sequences 

Within character and string constants the backslash (‘\’) is a special character which is used to represent non printable characters or hard to print characters. When backslash is used in conjunction with one or more characters to create a sequence of characters then it is called escape sequence.

Escape Sequence	Meaning
\a	Alert
\b	Backspace
\t	Horizontal tab
\v	Vertical tab
\n	New line
\f	Form feed
\r	Carriage return
\\	Backslash
\’	Single quotes
\”	Double quotes
\?	Question mark

5) Named Constants 

Enumerators are the named constants that are used to give names to elements of finite set. Set of these named constants are called enumeration.

Enumeration types are internally treated as integers by the compilers.

Declaration of enumeration types-

enum fruit{apple,banana,mango,guava};

by default, enumerators starts from 0,1 and so on. Here apple will take value 0, banana 1, mango 2 and guava 3.

6) Symbolic Constants 

Symbolic constant is the name that substitutes for a constant. The constants can be numeric constant, character constant, string constant.

The pre-processor directive #define is used to define symbolic constants.

e.g.     #define pi 3.14

#define false 0

This chapter about elements of C language covered a brief description about elements of C Language. More on the same would be published in the coming Chapters.

Similar Topic   :  C Language Introduction

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