C Programming Language is the most popular computer language and most used programming language till now. It is very simple and elegant language. This lecture series will give you basic concepts of structured programming language with C.

1. Operators and Expressions
Md. Imran Hossain Showrov (showrovsworld@gmail.com)
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2. Outline
 Operands
 Arithmetic Operators
 Unary Operators
 Relational and Logical Operators
 Assignment Operator
 Conditional Operator
 Operator Precedence Groups

3. Operands
 The data items that operators act upon are called
operands.
 Some operators require two operands(a+b, a-b),
while others act upon only one operand(i++, i--).

4. Arithmetic Operators
 There are five arithmetic operators in C. They are
Operator Purpose
+ Addition
- Subtraction
* Multiplication
/ Division
% Remainder after
integer division

5. Arithmetic Operators (cont..)
 The % operators is sometimes referred as the
modulus operator.
 The remainder operator (%) requires that both
operands be integers and second operand be
nonzero.

6. Arithmetic Operators (cont..)
 Division (/) of one integer quantity by another is
referred to as integer division that always results in a
truncated quotient (the decimal portion of the
quotient will be dropped).
 If a division operation is carried out with two
floating-point numbers or with one floating-point
number and one integer, the result will be a floating-
point quotient.

7. Arithmetic Operators (cont..)
 Suppose that a and b are integer variables and a = 10
and b = 3.
Expression Value
a + b 13
a – b 7
a * b 30
a / b 3
a % b 1

8. Arithmetic Operators (cont..)
 Suppose that v1 and v2 are floating-point variables
and v1 = 12.5 and v2 = 2.0.
Expression Value
v1 + v2 14.5
v1 – v2 10.5
v1 * v2 25.0
v1 / v2 6.25

9. Unary Operators
 Unary operator is a class of operator that act upon a
single operand to produce a new value.
 The most common unary operation is unary minus, where
a numerical constant, variable or expression is preceded
my a minus sign.
 Example: -743 -0.2 -3 * (x+y)
 There are two other commonly used unary operators:
1. The increment operator (++)
2. The decrement operator (--)

10. Unary Operators (cont..)
 Suppose that i is an integer variable that has been
assigned a value of 5.The expression ++i, which is
equivalent to writing i = i + 1, cause the value of i to
be increased to 6. Similarly, the expression --i, which is
equivalent to i = i - 1, cause the (original) value of i to
be decreased to 4.

11. Unary Operators Example 1
 Lets see an example…
a = 10; b = 20;
x = ++a;
y = b++;
printf(“x = %d a = %dn”,x , a);
printf(“y = %d a = %dn”,y , a);

12. Unary Operators Example 1 (cont..)
Here, x = ++a statement is equivalent to following two statement
a = a + 1;
x = a;
Thus the value of x will be 11.
On the other hand, y = b++ is equivalent to
y = b;
b = b+1;
So, the value of y will be 20 and b will be 21.

13. Unary Operators Example 2
Lets do these exercise together:
Here, a = 10; b = 20;
1. x = 50 + ++a;
2. y = 100 + b++;
3. x = a++ - ++a;

14. Relational and Logical Operators
 There are four relational operators.They are
 Closely associate with the relational operators are
Operator Meaning
< Less than
<= Less than or equal to
> Greater than
>= Greater than or equal to
Operator Meaning
== Equal to
!= Not equal to

15. Relational and Logical Operators
(cont..)
 Relational Operator example 1: suppose that i, j
and k are integer variables whose values are 1, 2 and
3, respectively.
Expression Interpretation Value
i < j true 1
(i + j) >= k true 1
(j +k) > (i + 5) false 0
k !=3 false 0
j == 2 true 1

16. Relational and Logical Operators
(cont..)
 Relational Operator example 2: Suppose that i is
an integer variable whose value is 7, f is a floating
variable whose value is 5.5, and c is a character
variable that express the character ‘w’
Expression Interpretation Value
f < 5 true 1
(i + f) <= 10 false 0
c == 119 true 1
c != ‘p’ true 1
C > = 10 * ( i + f) false 0

17. Relational and Logical Operators (cont..)
 C contains two logical operators. They are..
 && is also referred as logical and
 || is also referred as logical or
Operator Meaning
&& and
|| or

18. Relational and Logical Operators (cont..)
 logical operators examples 1: Suppose that i is an
integer whose value is 7, f is a floating-point variable
whose value is 5.5, and c is a character variable that
represents the character ‘w’.
Expression Interpretation Value
(i >=6) && (c == ‘w’) true 1
(I >=6) || (c == 119) true 1
(f < 11) && (I >100) false 0
(c != ‘p’) || ((I + f) <=
10)
true 1

19. Relational and Logical Operators (cont..)
 logical operators examples 1: Suppose that i is an
integer whose value is 7, f is a floating-point variable
whose value is 5.5, and c is a character variable that
represents the character ‘w’.
Expression Interpretation Value
(I + f) <= 10 false 0
(i >=6) && (c == ‘w’) true 1
(c = ‘p’) || ((I + f) <=
10)
false 0

20. Relational and Logical Operators (cont..)
 logical operators examples 1: Suppose that i is an
integer whose value is 7, f is a floating-point variable
whose value is 5.5, and c is a character variable that
represents the character ‘w’.
Expression Interpretation Value
(I + f) <= 10 false 0
(i >=6) && (c == ‘w’) true 1
(c = ‘p’) || ((I + f) <=
10)
false 0

21. Assignment Operator
 The most commonly used assignment operator is ‘=’
 identifier = expression
 Example:
 a = 3;
 x = y;
 sum = a + b;
 And so on….

22. Conditional Operator
 Simple conditional operations can be carried out with
the conditional operator(? :).
 A conditional expression is written in the form
expression 1 ? expression 2 : expression 3
 When evaluating a conditional expression, expression 1
is evaluated first.
 If expression 1 is true, than expression 2 is evaluated and this
become the value of the conditional expression.
 If the expression 1 is false, then expression 3 is evaluated and
this become the value of the conditional expression.

23. Conditional Operator Example
 Let i = 5
So, flag = (i < 0) ? 0 : 100
Output will be 100 as expression 1 (i < 0) is false.
 Let, f = 8 and g = 9
So, min = (f < g) ? f : g
Output will be 8 as expression 1(f<g) is true.

24. Operator Precedence Groups
Operator Category Operators Associativity
unary operators - ++ -- ! sizeof(type) R -> L
arithmetic multiply,
divide, remainder
* / % L -> R
arithmetic add and
subtract
+ - L -> R
relational operators < <= > >= L -> R
equality operators == != L -> R
logical and && L -> R
logical or || L -> R
conditional operator ? : R -> L
assignment operators = += -+ *= /= %= R -> L