Slides for a talk

1. Established as per the Section 2(f) of the UGC Act, 1956
Approved by AICTE, COA and BCI, New Delhi
Templates &
Exception Handling in C++
N i m r i t a K o u l
N i m r i t a . k o u l @ r e v a . e d u . i n

2. C ++ TEMPLATES - OUTLINE
• Quick Recap
• What are Templates?
• Why use templates?
• Function Templates
• Class Templates
• Summary
• Programs

3. EXCEPTION HANDLING-
OUTLINE
• What is an Exception?
• How is it Handled?
• What are try, catch and throw
• Handling derived class exceptions
• Programs

4. RECAP: FEATURES OF C++
Image Source: https://dataflair.com

5. APPLICATIONS OF C++PROGRAMMING
Source: www.sitebay.com

6. PLATFORM INDEPENDENCE

8. C++ TEMPLATES

9. DEFINITION
A template is a pattern or amold, that serves as a guide for manufacture of some articles.

10. DOCUMENT TEMPLATES

11. MORE TEMPLATES

12. TEMPLATES FOR PROGRAMMING -GENERIC PROGRAMMING

13. WHY GENERIC PROGRAMMING?
1. With a strongly-typed language we need to write different versions of a function that does same operations
ondifferent types ofinput parameters.
2. This leads tolargecode(code bloat), canbe tedious, error prone andtime-consuming.
So what is the
solution?

14. SOLUTION IS TO USE TEMPLATES
USE OF TEMPLATES FOR FUNCTIONS AND CLASSES ALLOWS US TO WRITE THE
CODE OF THESE FUNCTIONS AND CLASSES WITHOUT EXACT SPECIFICATION OF
THE DATATYPES ON WHICH THESE FUNCTIONS OR CLASSES OPERATE.
THE DATATYPES CAN BE SPECIFIED LATER WHEN THESE FUNCTIONS OR CLASSES ARE
ACTUALLY USED.
THE COMPILER GENERATES A DIFFERENT CODE FOR EACH DATATYPE OF THE
PARAMETERS PASSED BY THE USER DURING ACTUAL USE OF THE TEMPLATE.

15. WHEN TO USE TEMPLATES?
Candidate functions for templates are those whose implementation remains
invariantover a set ofinstances.
That is, the algorithmic behavior of the code is the same, independent of the
typeof objects thealgorithmis processing.
FUNCTION TEMPLATES CLASS TEMPLATES

16. DEFINING A FUNCTION TEMPLATE

17. keyword template always begins a definition and declaration of a function template
<> brackets contain a list of template parameters
keyword ’typename’ or ‘class’ tells the compiler that
what follows is the name of a type
To use the template function you call it with the
required type in angle-brackets.
The compiler will generate a new function for each
new type parameter you supply

18. IMPLICIT DEDUCTION AND EXPLICIT SPECIFICATION OF RETURN TYPE OF TEMPLATE
In many cases the
template type
can be deduced
from the
invocation of the
function
For example min has two
arguments and a return type
all of the same type.
In the call min(10,20) both
arguments are integers,
therefore the compiler can
deduce that typename
T maps onto int
If it cannot deduce the type
from the argument –
e.g. min (10, 20.9), then a
compiler error message is
generated. This can be
resolved by forcing the type
using explicit instantiation

19. DATATYPES IN TEMPLATE DEFINITION AND USE, MUST MATCH

20. EXPLICIT SPECIFICATION OF RETURN TYPE

21. WHAT HAPPENS IN THE BACK GROUND OF TEMPLATE PROCESSING
New code is generated for each
new type that the compiler
encounters.
The compiler uses the template
code to generate a new
function with the template
parameter replaced by the
supplied type.
A template instance is only created
once.
If multiple calls
to min with int or double arguments
are encountered (or any type for
that matter) then still only one set
of object code is created per
translation unit.

23. TEMPLATE FUNCTIONS CAN BE OVERLOADED

24. EXAMPLES – TEMPLATE FUNCTION TO FIND LARGEST OF TWO NUMBERS

26. OUTPUT

27. EXAMPLE 2: SWAP DATA USING FUNCTION TEMPLATES

28. CONTD.

29. OUTPUT

30. CLASS TEMPLATES
1. Whenever you Need To
Implement A Generic Class That
Performs Similar Operations On
Different Types Of Data.
Use A Template Class.
2.This Way You Do Not Need To
Create A Different Class For Each
Data Type. Or You Do Not Need To
Create Different Member Variables
And Functions Within A Single Class
For Different Data Types.
3. Advantage is that using
template class reduces code size,
and make code easy to maintain
as any change will need to be
done only on the template.
4. Class templates make it easy
to reuse the same code for all
data types

31. HOW TO DECLARE A CLASS TEMPLATE?
T is the template argument which is a placeholder for the data type used
Inside the class body, a member variable var and a member function
someOperation() are both of type T.

32. HOW TO CREATE OBJECT OF TEMPLATE CLASS

33. EXAMPLE –SIMPLE CALCULATOR

36. ADVANTAGES OF TEMPLATES
Utility: High utility when we combine it with function overloading and multiple inheritances.
Less Redundancy: The same template once defined can be used for several data types. For
example, if we want to find the area of a rectangle with parameters entered as integer values as
well as floating-point values, we can effortlessly achieve this task with the implementation of
templates without having to create separate functions for integer and floating point data
Reduced Programming Effort: Drastically reduces the programming effort on the user’s end as the
same fragment of code can be used for multiple data types
Reusability and Flexibility: Same fragment of code can be used for multiple data types, providing
flexibility at the user-end to enter any type of data.

37. TEMPLATE PROGRAMS ON IDE

38. EXCEPTION HANDLING

39. Source: www.dataflair.com

40. EXCEPTION IS AN OCCURRENCE THAT IS NOT NORMAL OR EXPECTED

41. EXAMPLE
1. Suppose you write aC++ program todivide two integers, it willwork perfectly wellnormally exceptwhen
thedenominatoriszerobecause that resultis mathematicallyundefined. So your compiler doesn’t
knowwhat todo inthis case and justhaltstheprogramorcrashes.
2. To prevent your program from crashing, youcanwritesomecodetotellthecompilerwhattodoin case
this situation arises. This is called exceptionhandling.

42. SO, WHAT IS AN EXCEPTION?
Exception - > An unexpected problem that occurs during the execution of a program and makes
the program crash
This problem arises because your program tries to do something that is not mathematically or
logically permissible. E.g. trying to divide by zero, trying to access 11th value in an array whose
maximum size is just 10, trying to read from a file that does not exist etc
Writing code in order to maintain the normal flow of the execution of the program when an
exception occurs is known as “Exception Handling”.

44. EXCEPTION HANDLING CYCLE

45. EXCEPTION HANDLING IN C++
Image Source: www.dataflair.com

46. TRY AND CATCH BLOCKS
In C++, exception handling is provided by using three constructs or keywords;
namely, try, catch and throw.
try block – The try keyword specifies the particular block of code in which the
programmer finds that exception handling needs to be implemented.
catch block -The catch keyword indicates that the C++ compiler has caught an
exception
Block of code that provides a way to handle the exception is called “exception
handler”.
The ‘throw’ keyword throws an exception to be handled by the user in other function
or by compiler.

47. GENERAL EXCEPTION HANDLER
try{
//code likelyto give exception
}catch(exception e){
//codeto process exception e
}
The code that is likely to throw exceptions is enclosed in the
“try” block
The try block can also contain a “throw” statement to
explicitly throw exceptions. The “throw” statement
consists of a keyword “throw” followed by a parameter
which is the exception name. This parameter is then
passed to the catch block
The exception thrown in the “try” block is passed on to
the “catch” block. The catch block contains the code to
process the thrown exception. It can contain merely a
message or an entire code block to process the exception
such that the normal flow of the program is not hindered

48. MULTIPLE CATCH BLOCKS
We can have multiple catch blocks
wherein each catch block provides
processing for each of the
exceptions generated in try block.

49. SYNTAX OF THROW STATEMENT
The ‘throw’
keyword throws an
exception to be
handled by the user
in other function or
by compiler.

50. SUMMARY

51. HIERARCHY OF EXCEPTIONS CLASS STD:: EXCEPTION IN C++

52. TYPES OF EXCEPTIONS IN C++

54. DIVISION BY ZERO WITHOUT EXCEPTION HANDLING

56. EXAMPLE – DIVISION BY ZERO

57. OUTPUT
Output:
Exception– Divisionby zero!!

58. CATCHING BASE AND DERIVED CLASSES AS EXCEPTIONS
We have learnt about inheritance in C++.
We have learnt about base and derived classes.
Our program can get an exception in both a base class and a derived class
To catch an exception for both base and derived class, we should put catch block
of derived class before the base class. Otherwise, the catch block of derived class
will never be reached

59. if we change the
order of catch
statements then
both catch
statements
become reachable

60. This modified program
prints “Caught Derived
Exception”

61. DEFINING NEW EXCEPTIONS
You can define your own exceptions by inheriting and
overriding exception class functionality.

63. OPPORTUNITIESAT SCHOOL OF CIT REVA
UNIVERSITY

64. OPPORTUNITIES AT SCHOOL OF CIT, REVA UNIVERSITY
• B.Tech(CSE)
• B.Tech(CS & IT)
• B.Tech(AI & ML)
• B.Tech(ISE)
• M.Tech( CSE)
• M.Tech (AI)
• Hackathons
• WorkshopsandSkill
• Development Programs
• International Internships andProject Expos
Latest Industry Oriented Curriculum -
• ProgrammingTechnologies -Cprogramming,Python
Programming,
Java Programming,R Programming etc.
• Web Technologies – PHP,Perl, Java Script, NodeJS,
Angular JSetc.
• Machine Learning, Deep Learning,
Blockchain,CloudComputing,Mobile
Application Development, DevOps,
Wireless and Sensor Networks
And manymore…

66. REFERENCES
• https://simplesnippets.tech/cpp-exception-handling/
• https://www.tutorialspoint.com/cplusplus/cpp_exceptions_handling.htm
• https://www.geeksforgeeks.org/exception-handling-c/
• https://www.tutorialspoint.com/catching-base-and-derived-classes-exceptions-in-cplusplus
• https://www.geeksforgeeks.org/g-fact-60/

67. EXCEPTION HANDLING PROGRAMS

68. THANK YOU