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3.1 Variables 3.1.1 Variable Declaration   Usually Variables are declared before use either at the start of a block of code after the opening { and before any other statements or outside a function. -------------------------- int a,b; /* global variables */ main() { float a; /* local variables */ } -------------------------- Local variables can only accessed within that function only whereas Global variables can access in whole program. 3.1.2 Variable Types   There are many 'built-in' data types in C. short int -128 to 127 (1 byte) unsigned short int 0 to 255 (1 byte) char 0 to 255 or -128 to +127 (1 byte) unsigned char 0 to 255 (1 byte) signed char -128 to 127 (1 byte) int -32,768 to +32,767 (2 bytes) unsigned int 0 to +65,535 (2 bytes) long int -2,147,483,648 to +2,147,483,647 (4 bytes) unsigned long int 0 to 4,294,967,295 (4 bytes) float single precision floating point (4 bytes) double double precision floating point (8 bytes) lon

 Operators An operator is a symbol. Compiler identifies Operator and performs specific mathematical or logical operation. C provides following operators : # Arithmetic Operators # Increment and Decrement Operators # Relational Operators # Logical Operators # Cast Operators # Bitwise Operators # Assignment Operators Arithmetic Operators * multiplication / division % remainder after division (modulo arithmetic) + addition - subtraction and unary minus  Increment and Decrement Operators Increment and decrement operators are used to add or subtract 1 from the current value of oprand. ++ increment -- decrement Increment and Decrement operators can be prefix or postfix. In the prefix style the value of oprand is changed before the result of expression and in the postfix style the variable is modified after result. For eg. a = 9; b = a++ + 5; /* a=10 b=14 */ a = 3; b = ++a + 6; /* a=10 b=15 */  Relational Operators == equal. != Not equal