1. Introduction to Programming – 4 Operators
Dr. Khizar Hayat
Associate Prof. of Computer Science

2. Operators Arithmetic operators Assignment operator, i.e. =
Compound assignment or arithmetic assignment operators
Increment and Decrement operators
Pre-increment
Post-increment
Relational operators
Logical Operators
Bit-wise logical operators

3. Arithmetic Operators I- Unary, e.g. -5, +7 II- Binary Addition (+)
Subtraction (-)
Multiplication (*)
Division (/)
Modulo division (%)
For example 11%3=2 or 33%5=3
Using ‘%’ for non-integer operands is a compilation error

4. Assignment operator The operator ‘=‘ assigns a value to a variable
e.g. the statement i=7; would assign a value 7 to variable i. in this case is the i Lvalue (left value) and 7 is the Rvalue (right value)
Note that:
Lvalue must always be a single variable.
The Rvalue may be a constant or a variable or an expression involving multiple variables and constants.
The assignment always takes place from right to left (right-to-left rule),
e.g. x=y; would assign the value of y to x; the value of y will be unchanged.

5. Assignment operator a=4 b=4 Output?
#include<iostream> using namespace std; int main() { int a,b; a=10; b=4; a=b; cout<<“a="<<a<<endl; cout<<“b="<<b<<endl; return(0); }
Output?
a=4
b=4

6. Compound assignment May be arithmetic or bit-wise logical Arithmetic:
+=, e.g. i+=3; means i=i+3;
-=, e.g. i-=1; means i=i-1;
*=, e.g. i*=7; means i=i*7;
/=, e.g. i/=2; means i=i/2;
%= , e.g. i%=10; means i=i%10;
Compound bitwise Logical work the same way but with logical bitwise operators, e.g. i|=77;

7. Increment/decrement operators
The unary Increment operator ++
count++;
is the same as,
count=count+1; or
count+=1;
The unary decrement operator --
count--;
count=count-1;
Count-=1;

8. Pre-increment and Post-increment
When the operator ++ comes before the variable then it is pre-increment.
, e.g. ++i; means first increase the value of i by 1 and then execute the statement
When the operator ++ comes after the variable then it is post-increment.
, e.g. i++; means first execute the statement and then increase the value of i by 1.
Same reasoning for pre- and post decrements, i.e. --j; and j--;

9. Example: Pre-increment and Post-increment
#include<iostream> using namespace std; int main() { int c; c=5; cout<<“c="<<c<<endl; cout<<“c="<<c++<<endl; cout<<“c="<<++c<<endl; cout<<c<<“\t"<<c++<<“\t"<<++c<<“\t"<<c++<<endl; //just for fun return(0); }

10. Relational Operators The relational operators evaluate to either
true (1) or
false (0)
In C++ the relational operators are:
== Equal to
!= Not equal to
> Greater than
< less than
>= Greater than or equal to
<= less than or equal to
Never confuse
== (equal to)
with
= (assignment or gets)

11. Examples What would the following expression evaluate to? (7==5)
//false 0
(5>4)
//true 1
(3!=2)
(6>=6)

12. Examples What would the following expression evaluate to?
Let int a=2,b=3,c=6;
(a==5)
//false
(a*b>=c)
//true
(b+4>a*c)
((b=2)==a)

13. Logical Operators The logical operators also evaluate to either:
true (1) or
false (0)
In C++ the Logical operators are:
! NOT Unary draw truth table
&& AND Binary draw truth table
|| OR Binary draw truth table
Bitwise logical operators are:
& bitwise AND
| bitwise OR
^ bitwise XOR
<< left shift
>> right shift

14. The ternary operator (? :) if-then-else
Also called the conditional operator
Use:
condition ? result1 : result1
(if true) (if false)
Examples:
7==5?4:3; //return 3
7==5+2?4:3; //return 4
a>b?a:b;/*return whichever greater,a or b */

15. Example ternary operator
#include<iostream> using namespace std; int main() { int a,b,c; a=2; b=7; c= (a>b)?a:b; cout<<“c = "<<c<<endl; return(0); }