The document discusses operators in the C programming language. It defines different types of operators such as arithmetic, relational, logical, and assignment operators. It provides examples of using various operators like addition, subtraction, multiplication, division, modulus, increment, decrement, relational, and logical operators. It also covers operator precedence and associativity rules for evaluating expressions containing multiple operators.

1. CSC 103
Lecture 5
Introduction to Computers and Programming

2. Evaluate yourself!
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 Point out the errors, if any, in the following C statements:
(a) int = 314.562 * 150 ;
(b) name = ‘Ajay’ ;
(c) varchar = ‘3’ ;
(d) 3.14 * r * r * h = vol_of_cyl ;
(e) k = ( a * b ) ( c + ( 2.5a + b ) ( d + e ) ;
(f) m_inst = rate of interest * amount in rs ;

3. Operators
 Operators are symbols that can be used to perform
certain calculations. They are always in between
expressions.
 Operators can be classified according to
 The number of their operands
 Unary (one operand)
 Binary (two operands)
 The type of their operands and of their output
 Arithmetic
 Relational
 Logical
 Bitwise
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4. Assignment operator: =
 Binary operator used to assign a value to a variable.
 Its left operand is the destination variable
 Its right operand is an expression.
int var;
var = 10;
COPY
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5. Arithmetic operators
 They operate on numbers and the result is a number.
 The type of the result depends on the types of the
operands.
 If the types of the operands differ, one is "promoted"
to other.
 The "smaller" type is promoted to the "larger" one.
char  int  float  double
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6. Arithmetic operators: +, *
 + is the addition operator
 * is the multiplication operator
 They are both binary
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7. Arithmetic operator: 
 This operator has two meanings:
 subtraction operator (binary)
 negation operator (unary)
e.g. 31 - 2
e.g. -10
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8. Arithmetic operator: /
 Division operator
 CAREFUL! The result of integer division is an integer:
e.g. 5 / 2 is 2, not 2.5
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9. Arithmetic operator: %
 The modulus (remainder) operator.
 It computes the remainder after the first operand is
divided by the second
 works only with integers
 It is useful for making cycles of numbers:
 For an int variable x :
if x is: 0 1 2 3 4 5 6 7 8
x%3 is: 0 1 2 0 1 2 0 1 2
e.g. 5 % 2 is 1,
6 % 2 is 0
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10. An Example
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#include <stdio.h>
void main (void)
{
int a = 25, b = 5, c = 10, d = 7;
printf ("a %% b = %in", a % b);
printf ("a %% c = %in", a % c);
printf ("a %% d = %in", a % d);
printf ("a / d * d + a %% d = %in",
a / d * d + a % d);
}
Output:
a % b = 0
a % c = 5
a % d = 4
a / d * d + a % d = 25

11. Using Arithmetic Operators
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#include <stdio.h>
void main (void)
{
int a = 100, b = 2, c = 25, d = 4,result;
result = a - b; // subtraction
printf ("a - b = %in", result);
result = b * c; // multiplication
printf ("b * c = %in", result);
result = a / c; // division
printf ("a / c = %in", result);
result = a + b * c; // precedence
printf ("a + b * c = %in", result);
printf ("a * b + c * d = %in", a * b + c * d);
}
Output:
a - b = 98
b * c = 50
a / c = 4
a + b * c = 150
a * b + c * d = 300

12. Relational operators
 These perform comparisons and the result is what is called a
Boolean: a value TRUE or FALSE
 FALSE is represented by 0; anything else is TRUE
 The relational operators are:
 < (less than)
 <= (less than or equal to)
 > (greater than)
 >= (greater than or equal to)
 == (equal to)
 != (not equal to)
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13. Logical operators
 These have boolean operands and the result is also a
boolean.
 The basic boolean operators are:
 && (logical AND)
 || (logical OR)
 ! (logical NOT) -- unary
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14. Special assignment operators
 write a += b; instead of a = a + b;
 write a -= b; instead of a = a - b;
 write a *= b; instead of a = a * b;
 write a /= b; instead of a = a / b;
 write a %= b; instead of a = a % b;
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15. Special assignment operators
 Increment, decrement operators: ++, --
 Instead of a = a + 1 you can write a++ or ++a
 Instead of a = a - 1 you can write a-- or --a
 What is the difference?
num = 10;
ans = num++;
num = 10;
ans = ++num;
First increment num,
then assign num to ans.
In the end,
num = 11
ans = 11
First assign num to ans,
then increment num.
In the end,
num =11
ans = 10
post-increment pre-increment
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16. Operator Hierarchy
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This expression
z = a * b + c / d
is same as;
z = (a * b) + (c / d)

17. Solve Following Expressions;
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&

18. Solution
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19. In C Language
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20. Associativity of Operators
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 We can have same priority operators in an expression
 Then we check associativity of operators
 There are two rules:
 Left to Right
 means that the operators are performed from left to right
 Right to Left
 means that the operators are performed from right to left