1. Computing Fundamentals
Instructor:
Engr.Romana Farhan
Assistant Professor CPED

2. Constants
Constants can not change their value during program execution.
There are 4 types of constants in C++
Integer constant
Floating point constant
Character constant
String constant
The const qualifier is used to make a variable constant.
Value to constant is initialized at its declaration.
const float pi=3.1416;

3. Example:
#include<iostream> using namespace std; int main() { Int r; const float p=3.14; float peri; r=2; peri=2*p*r; cout<<“result is=“<<peri; return 0; }

4. Example
Compile-Time Error

5. The “define” directive
#define directive is also used to define a constant quantity.
Following is the syntax of #define directive
#define identifier constant
Example
#define pi
NOTE:
The identifier does not have any data type and any value can be assigned to it.
The name of identifier can not be used in the program.

6. Example:
#include<iostream> #define p 3.14 using namespace std; int main() { int r; float peri; r=2; peri=2*p*r; cout<<“result is=“<<peri; return 0; }

7. Example:
#include <iostream> using namespace std; int main () { int i; cout << "Please enter an integer value: "; cin >> i; cout << "The value you entered is " << i; cout << " and its double is " << i*2 << ".\n"; return 0; }

8. Arithmetic Operators

9. Arithmetic operators
All the operators on previous slide are binary operators as they require two operands.
C++ applies the operators in arithmetic expressions in a precise sequence determined by the following rules of operator precedence, which are generally the same as those followed in algebra

10. Operator precedence

11. Arithmetic Expression Evaluation
Evaluate
Y = 2*5*5+3*5+7;
Y=(4-(3*5))+2
What is your answer?

13. C++ Programming Guidelines
From Deitel and Deitel

14. Relational Operators
Relational operators specify a relationship between two operands. The operands may be variables, constants or expressions.
a >= b
10 < 20
( a + b ) > ( c * d )
The relational operators along with the operands form a relational expression.
The result of a relational expression is either true or false.

15. Relational Operators

16. Note:-

17. Logical Operators
C++ provides logical operators that are used to form complex conditions by combining simple conditions.
The logical operators are
&& (logical AND)
|| (logical OR)
! (logical NOT, also called logical negation).

18. Logical Operators - &&
The && (logical AND) operator is used to ensure that two conditions are both true before we choose a certain path of execution.
The simple condition to the left of the && operator evaluates first.
If necessary, the simple condition to the right of the && operator evaluates next.
The right side of a logical AND expression is evaluated only if the left side is true.

19. Logical Operators - &&

20. Logical Operators - ||
The || (logical OR) operator determines if either or both of two conditions are true before we choose a certain path of execution.
If any one of the simple conditions to the left or right of || is true, the output will be true.
The && operator has a higher precedence than the || operator.
Both operators associate from left to right.

21. Logical Operators - ||

22. Logical Operators - !
C++ provides the ! operator (logical NOT) which is also called logical negation operator.
It “reverses” a condition’s meaning, i.e., if (x>y) is true then !(x>y) will be false.
The unary logical negation operator has only a single condition as an operand.

23. Logical Operators - !

24. Find out …
What is short-circuit evaluation in context of && and || operators?

25. Assignment Operator
C++ provides several assignment operators for abbreviating assignment expressions.
Any statement of the form
variable = variable operator expression;
in which the same variable appears on both sides of the assignment operator and operator is one of the binary operators +, -, *, /, or % , can be written in the form
variable operator= expression;
Thus the statement c = c + 3 which adds 3 to c can be written as c += 3

26. Assignment Operator

27. Example: Sol: #include<iostream> using namespace std; int main()
Write a program in c++ to assign three values to three integers a,b,c. Add variables a & b and multiply their sum to variable c by using compound assignment statements.
Sol:
#include<iostream>
using namespace std;
int main() {
int a,b,c;
a=3; b=6;c=9;
c*= a+b;
cout<<“result=“<<c; }

28. Increment and Decrement Operators
C++ also provides two unary operators for
adding 1 to value of a variable or
subtracting 1 from the value of a numeric variable.
These are the
unary increment operator ++
unary decrement operator --

29. Increment and Decrement Operators

30. Prefix increment Operator
#include<iostream> using namespace std; int main() { int a,b,c,sum; a=1,b=1,c=3; sum=a+b+(++c); cout<<"sum="<<sum; //sum=6 cout<<"c="<<c; //c=4 return 0; }

31. Postfix Increment Operator
#include<iostream> using namespace std; int main() { int a,b,c,sum; a=1,b=1,c=3; sum=a+b+(c++); cout<<"sum="<<sum; //sum=5 cout<<"c="<<c; //c=4 return 0; }

32. Prefix Decrement Operator
#include<iostream> using namespace std; int main() { int a,b,c,sum; a=1,b=1,c=3; sum=a+b+(--c); cout<<"sum="<<sum; //sum=4 cout<<"c="<<c; //c=2 return 0; }

33. Postfix decrement Operator
#include<iostream> using namespace std; int main() { int a,b,c,sum; a=1,b=1,c=3; sum=a+b+(c--); cout<<"sum="<<sum; //sum=5 cout<<"c="<<c; //c=2 return 0; }

36. Questions