Data Types
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Introduction
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To communicate with the computer, it
is required to pass an appropriate value to the computer from the keyword.
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The value passed may be of different
types, viz. Single character, integer, decimal, string.
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In each, the memory required is of
different size. Such a defined type of value is called data type.
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C supports several different types of
data, each of which may be represented differently within the computers
memory.
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The memory requirement of each data
type will determine the permissible range of values for that data type.
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C data type can be broadly divided in
two categories:
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(a) Primary data types.
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(b) Secondary data types.
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Primary data types
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Primary data types are independent
data types. It's not derived from other basic or secondary data types.
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There are five primary data types in
C language:
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1. Void
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2. Character
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3. Integer
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4. Float
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5. Double
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Secondary data types
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Secondary data types are also called
as derived data types. Secondary data types are derived from the basic data
types.
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They are also five in number:
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1. Array
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2. Pointer
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3. Structure
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4. Union
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5. Enum
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Primary Data Type
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1. Void
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Description:
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Used to specify empty set containing
no values.
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Storage Space: 0 byte.
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Format: (void).
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Range of values: ______.
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2. Character (Denoted as
"char" in C programming language)
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Description:
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A character denotes any alphabet,
digit or special symbol used to represent in formation and it is used to
store a single character.
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Storage space: 1 byte
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Format: %c
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Range of Values: ASCII Character
Set.
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3. Integer (Denoted as
"int" in C programming language)
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Description:
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Integer type is used to store
positive and negative integer.
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Storage space: 2 bytes.
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Format: %d
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Range of values: -32768 to +32767.
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4. Float
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Description:
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It is used to store real number, with
single precision floating point number (precision of 6 digits after decimal
points.)
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Storage space: 4 bytes.
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Format: %f
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Range of values: -3.4*1038 to
+3.4*1038.
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5. Double
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Description:
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It stores real numbers with double
precision. The use of double doesn't guarantee to double the number of
significant digits in our result, but it improves the accuracy of the
arithmetic and reduces the accumulation of rounding errors.
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Storage Space: 8 bytes.
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Format: %ld
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Range of values: -1.7*10308 to
+1.7*10308.
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Explanation: Numeric data stored is stored in the memory
in their binary form, while the character data has to be codified as a unique
integer and that code number is stored in the internal storage.
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The integer equivalents of alphabets
are:
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Lower case: a-z = 97 to 122
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Upper case: A-Z = 65 to 90
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In the above program when the
characters are displayed in the integer format the
correspondingASCII code are displayed, similarly when integers are
displayed in the character format then equivalent character
is displayed.
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Secondary Data Type
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1. Array:
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It is a collection of data of similar
data type.
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e.g. Int num [5];
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Reserve a sequence of 5 location of
two bytes each for storing integers.
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2. Pointer:
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Pointer is a variable that stores the
address of some other variable.
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e.g. int *i;
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The above statement declares i as
pointer to integer data type.
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3. Structure:
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A structure is a collection of data
of different data types under one name.
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e.g.
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Struct employees
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{
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char Name[10];
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int Age;
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int Salary;
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}
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4. Union:
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It is a collection of data of different
types sharing common memory space.
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e.g. Union item
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{
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int m;
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float x;
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char c;
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} ;
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5. Enumerated Data types:
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This data types gives us an
opportunity to invent your own data type and define what values the variable
of this data type can take.
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Example: enum colors
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{
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red, green, blue, cyan
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};
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colors foreground, background;
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Here the declaration has two parts:
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a) The first part declare the data
type and specifies its possible values.
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b) The second part declare variable of
this data type.
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Now we can give the values to these
variables:
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foreground=red;
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background=blue;
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But remember we can't use values that
aren't in the original declaration. Thus, the following declaration cause
error.
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foreground=yellow;
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Note: Secondary data type has been given in
detail later.
More Topics
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