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Operators in C programming : Special Operators

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C supports some special operators such as comma operator, size of operator, pointer operator (* and &) and member selection operators. (.and  →)

Comma Operator:
The comma operator can be used to link the related expression together. Comma linked lists of expression are evaluated left to right and the value of right-most expression is the value of combined expression. For example, value = (x = 10, y = 5, x + y),
Here, 10 is assigned to x and 5 is assigned to y and so expression x+y is evaluated as (10+5) i.e. 15.

Size of Operator:
The size of operator is used with an operand to return the number of bytes it occupies. It is a compile time operand. The operand may be a variable, a constant or a data type qualifier. The associativity of size of right to left. For example Suppose that i is an integer variable, x is a floating-point variable, d is double-precision variable and c is character type variable.
The statements:
printf (“integer : %d \n”, size of i) ;
printf (“float : %d \n”, size of x) ;
printf (“double : %d \n”, size of d) ;
printf (“character : %d \n”, size of c) ;

Unary expression                              Equivalent expression
++ variable or (variable ++)               variable = variable +1
-- variable or (variable _ _)                 variable = variable -1

The investment or decrement operators can each be utilized two different ways, depending on whether the operator is written before or after. If the operator is written before the operand then it is called as prefix unary operator. If the operator is written after the operand, then it is called as postfix unary operator. When prefix is used, the operand will be altered in value before it is utilized for its intended purpose within the program. Similarly, when postfix is used, the operand will be altered in value after it is utilized. A C program includes an integer variable i whose initial value is 1. Suppose the program includes the following three printf statements.
printf (“i = %d\n”, i) ;
printf (“i = %d\n”, ++i) ;
printf (“i = %d\n”, i) ;
These printf statements will generate the following three lines of output:
i = 1
i = 2
i = 2
Again, suppose            printf (“i = %d\n”, i) ;
printf (“i = %d\n”, i++) ;
printf (“i = %d\n”, i) ;
These statements will generate the following three lines of output:
i = 1
i = 1
i = 2
The precedence of unary increment or decrement is same and associativity is right to left.
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