C TOKEN , VARIABLES AND DATA TYPES
C-TOKENS
Tokens are smallest individual units in C program.
There are 6 types of tokens
Keyword
String
Identifier
Operator
Constant
Special symbol
KEYWORDS
They are reserved words used in programming ,each keywords has a pre-defined meaning and that cannot be changed .
Example int , char ,float ,double etc
STRINGS
The array of character are called strings, A string is terminated with a null character .
Example "My course BCA "
Declaration of strings
Char s[5];
Strings are declared similar to arrays, the difference is string of char data type.
IDENTIFIERS
Identifiers are names given to C entities ,such as variables ,function,structures etc.
Example
Int car;
Here, car is a identifier which is a variable of type integer .
Rules for identifers
1. Identifiers should be composed of letters ,digits and underscore.
2. The first letter of identifier should be either a letter or underscore.
3. There is no rule for length of the identifer.
OPERATOR
They are symbols which operate on value or variables.
Example : '+' operator is used for addition.
Different operator in c
Arithmetic operator.
Increment and decrement operator.
Assignment operator.
Relational operator.
Conditional operator.
Bitwise operator.
Special character.
CONSTANTS
The constants refer to fixed values that the program may not alter during its execution. These fixed values are also called literals.
Constants can be of any of the basic data types like an integer constant, a floating constant, a character constant, or a string literal. There are also enumeration constants as well.
The constants are treated just like regular variables except that their values cannot be modified after their definition.
Integer literals
An integer literal can be a decimal, octal, or hexadecimal constant. A prefix specifies the base or radix: 0x or 0X for hexadecimal, 0 for octal, and nothing for decimal.
214 /* Legal */
0xFeeL /* Legal */
078 /* Illegal: 8 is not an octal digit */
Floating-point literals
A floating-point literal has an integer part, a decimal point, a fractional part, and an exponent part. You can represent floating point literals either in decimal form or exponential form.
3.14159 /* Legal */
314159E-5L /* Legal */
510E /* Illegal: incomplete exponent */
Character constants
Character literals are enclosed in single quotes, e.g., 'x' and can be stored in a simple variable of char type.
A character literal can be a plain character (e.g., 'y'), an escape sequence (e.g., '\t'), or a universal character (e.g., '\u02C0').
String literals
String literals or constants are enclosed in double quotes "". A string contains characters that are similar to character literals: plain characters, escape sequences, and universal characters.
You can break a long line into multiple lines using string literals and separating them using whitespaces.
Examples
"hello, dear"
Defining Constants
There are two simple ways in C to define constants:
Using #define preprocessor.
Using const keyword.
The #define Preprocessor
Following is the form to use #define preprocessor to define a constant:
#define identifier value
The const Keyword
You can use const prefix to declare constants with a specific type as follows:
const type variable = value;
Special values
The special values used in c are ( ) " ; # % / { } [ ]
VARIABLES
Variables are memory location in computer memory to store data, to indicate the memory location ,each variable should be
Given a unique name called identifier.
Variable names are just symbolic representation of memory location.
Example : car , Door_No etc.
Rules for writing variables are same as of identifiers.
Declaration of variables
Int num;
Here num is variable of data type int , similarly you can use char , float double for declaring different variables.
Initialization of variables
Num=10;
Assigning values to the variables is known as initialization.
DATA TYPES
In the C programming language, data types refer to an extensive system used for declaring variables or functions of different types. The type of a variable determines how much space it occupies in storage and how the bit pattern stored is interpreted.
The data types in C can be classified as follows:
1 Basic Types
They are arithmetic types and consists of the two types:
(a) integer types and
(b) floating-point types.
2 Enumerated types
They are again arithmetic types and they are used to define variables that can only be assigned certain discrete integer values throughout the program.
3 The type void:
The type specifier void indicates that no value is available.
4 Derived types:
They include
(a) Pointer types,
(b) Array types,
(c) Structure types,
(d) Union types and
(e) Function types.
INTEGER DATA TYPES
FLOATING DATA TYPE
C-TOKENS
Tokens are smallest individual units in C program.
There are 6 types of tokens
Keyword
String
Identifier
Operator
Constant
Special symbol
KEYWORDS
They are reserved words used in programming ,each keywords has a pre-defined meaning and that cannot be changed .
Example int , char ,float ,double etc
STRINGS
The array of character are called strings, A string is terminated with a null character .
Example "My course BCA "
Declaration of strings
Char s[5];
Strings are declared similar to arrays, the difference is string of char data type.
IDENTIFIERS
Identifiers are names given to C entities ,such as variables ,function,structures etc.
Example
Int car;
Here, car is a identifier which is a variable of type integer .
Rules for identifers
1. Identifiers should be composed of letters ,digits and underscore.
2. The first letter of identifier should be either a letter or underscore.
3. There is no rule for length of the identifer.
OPERATOR
They are symbols which operate on value or variables.
Example : '+' operator is used for addition.
Different operator in c
Arithmetic operator.
Increment and decrement operator.
Assignment operator.
Relational operator.
Conditional operator.
Bitwise operator.
Special character.
CONSTANTS
The constants refer to fixed values that the program may not alter during its execution. These fixed values are also called literals.
Constants can be of any of the basic data types like an integer constant, a floating constant, a character constant, or a string literal. There are also enumeration constants as well.
The constants are treated just like regular variables except that their values cannot be modified after their definition.
Integer literals
An integer literal can be a decimal, octal, or hexadecimal constant. A prefix specifies the base or radix: 0x or 0X for hexadecimal, 0 for octal, and nothing for decimal.
214 /* Legal */
0xFeeL /* Legal */
078 /* Illegal: 8 is not an octal digit */
Floating-point literals
A floating-point literal has an integer part, a decimal point, a fractional part, and an exponent part. You can represent floating point literals either in decimal form or exponential form.
3.14159 /* Legal */
314159E-5L /* Legal */
510E /* Illegal: incomplete exponent */
Character constants
Character literals are enclosed in single quotes, e.g., 'x' and can be stored in a simple variable of char type.
A character literal can be a plain character (e.g., 'y'), an escape sequence (e.g., '\t'), or a universal character (e.g., '\u02C0').
String literals
String literals or constants are enclosed in double quotes "". A string contains characters that are similar to character literals: plain characters, escape sequences, and universal characters.
You can break a long line into multiple lines using string literals and separating them using whitespaces.
Examples
"hello, dear"
Defining Constants
There are two simple ways in C to define constants:
Using #define preprocessor.
Using const keyword.
The #define Preprocessor
Following is the form to use #define preprocessor to define a constant:
#define identifier value
The const Keyword
You can use const prefix to declare constants with a specific type as follows:
const type variable = value;
Special values
The special values used in c are ( ) " ; # % / { } [ ]
VARIABLES
Variables are memory location in computer memory to store data, to indicate the memory location ,each variable should be
Given a unique name called identifier.
Variable names are just symbolic representation of memory location.
Example : car , Door_No etc.
Rules for writing variables are same as of identifiers.
Declaration of variables
Int num;
Here num is variable of data type int , similarly you can use char , float double for declaring different variables.
Initialization of variables
Num=10;
Assigning values to the variables is known as initialization.
DATA TYPES
In the C programming language, data types refer to an extensive system used for declaring variables or functions of different types. The type of a variable determines how much space it occupies in storage and how the bit pattern stored is interpreted.
The data types in C can be classified as follows:
1 Basic Types
They are arithmetic types and consists of the two types:
(a) integer types and
(b) floating-point types.
2 Enumerated types
They are again arithmetic types and they are used to define variables that can only be assigned certain discrete integer values throughout the program.
3 The type void:
The type specifier void indicates that no value is available.
4 Derived types:
They include
(a) Pointer types,
(b) Array types,
(c) Structure types,
(d) Union types and
(e) Function types.
INTEGER DATA TYPES
FLOATING DATA TYPE
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