Data types:

C language is rich in its data types. ANSI supports three classes of

data types.

1) Primary or fundamental data types.

2) Derived Data types.

3) User-defined data types.

1) Fundamental Data types:

All C compilers support five fundamental data types.

 Integer (int)

 Character (char)

 Floating point (float)

 Double-precision point (double)

 Void

i. Integer types:

Integer types are whole numbers with a range of values supported by particular machine. If we use a 16 bit word length, the size of the integer value is limited to the range -32768 to +32767. C has three classes of integer storage namely

 Short int

 Int

 Long int

Short int represents small values than int and int represents small value than long int. or we can say that Short int < int < long int

 Here 1 byte = 8 bits.

 Signed int is able to represent negative values.

 Unsigned int can represent non-negative values (positive

values).

ii. Floating point types:

 Floating point numbers are stored in 32 bits, with 6 digits of precision.

 Floating point numbers are defined in C by keyword float.

 When float is not sufficient double can be used and when double is not sufficient long double can be used.

 The following table provide the details of standard floating point types with storage size and value ranges and their precision,

iii. Void types:

 The void type has no values. This is usually used to specify the types of functions.

 The types of function is said to be void when it does not return any values to the calling function.

iv. Character types:

 A single character can be defined as character (char) type data.

 Characters are usually stored in 8 bits (1 byte) of internal storage.

 While unsigned char have values between 0 to 255, sign char have values from -128 to 127. Declaring & initialization of C variable:

 Declaration:

 Variables must be declared in C program before use.

 In C language variable is declared using following syntax:

 Syntax: Data type variable name;

 Example:

int sum; Here, int is data types and sum is the name of variable. Multiple variables can be declare like,

Example:

int sum, total, a;

float p, r;

 Initialization: 

o Variable initialization means assigning a value to the variable.

Example:

int sum=30;

Here variable sum is declared and at the same time it is assigned a value 30. Declaring variable as constant Variable can be declared as constant using keyword const.

Example:

const int sum =30;

OR

int const sum=30;

 Here, Variable sum is declared as const it means that the value of variable sum cannot be changed latter in program.

 Any attempt to change the value of sum will result in error.

 Const keyword can be used before or after data type.