Exception handling

 An exception is a situation which is unusual
for a program that is being processed
What is Exception Handling ?
The ability to deal with a program’s eventual
abnormal behavior is called Exception handling.

C++ provides three keywords to
1. Try (Trying the normal flow)
2. Catch (Catching Errors)
3. Throw (Throwing an error)
handle an exception.

Syntax: try {Behavior}
Try (Trying the normal flow)
It lets the compiler know that you are
anticipating an abnormal behavior and will try
to deal with it.

Syntax: catch(Argument) {WhatToDo}
Catch (Catching Errors)
During the flow of the program as part of the
try section
 if an abnormal behavior occurs, instead of
letting the program crash
you can transfer the flow of the program to
another section that can deal with it and that
section is Catch Section.

try {
CCoommbbiinneedd wwiitthh tthhee ttrryy bblloocckk,,
tthhee ssyynnttaaxx ooff aann eexxcceeppttiioonn wwoouulldd bbee::
// Try the program flow
}
catch(Argument)
{
// Catch the exception
}

We can also chain multiple handlers (catch
expressions), each one with a different
parameter type
try {
// code here
}
catch (int param)
{ cout << "int exception";
}
catch (char param)
{ cout << "char exception";
}
catch (...)
{ cout << "default exception";
}

The transfer of control from the try block to
the catch clause is carried by the throw
keyword.
Eg :
throw ;
throw "Positive Number Required";
TThhrrooww ((TThhrroowwiinngg aann eerrrroorr))

NNooww
LLeett''ss FFaaccee
SSoommee EExxcceeppttiioonnss......

#include <iostream>
int main()
{
double Number1, Number2, Result;
// Request two numbers from the user
cout << "Please provide two numbersn";
try {
cout << "First Number: ";
cin >> Number1;
cout << "Second Number: ";
cin >> Number2;

if( Number2 == 0 )
throw"Cant divide by zero";
// Perform a division and display the result
Result = Number1 / Number2;
cout << "n" << Number1 << " / " << Number2 << " = " << Result
<< "nn";
}
catch(const char* Message)
{ cout << "Error: " << Message;
}
getch();
return 0;
}

WWhheenn YYoouu FFaaccee AAnn EExxcceeppttiioonn

NNooww
LLeett''ss FFaaccee
AAnnootthheerr EExxcceeppttiioonn......

#include<conio.h>
#include<iostream.h>
class factorial
{ int i,fact;
public:
void facto(int n)
{ fact=1;
for(i=1;i<=n;i++)
{ fact=fact*i;
}
cout<<"Factorial of a given no. is"<<fact;
}
};

int main()
{ clrscr();
int n;
factorial f;
cout<<"Enter no.n";
cin>>n;
try
{ if(n<0)
throw"Please Enter natural no !!!";
f.facto(n);
}
catch(const char *message)
{ cout<<"Error:"<<message;
}
getch();
return 0;
}

Q1. Identify tthhee ccoorrrreecctt ssttaatteemmeenntt ??
1. There must not be any code between the try’s
closing bracket and the catch section.
2. There can be any code between the try’s closing
bracket and the catch section.
3. There may be any code between the try’s closing
4. There must be any code between the try’s closing

QQ22.. TThheerree ccaann bbee mmuullttiippllee ccaattcchh
bblloocckk iinn pprrooggrraamm ??
1. True
2. False

QQ33.. WWhhiicchh ooff tthheessee llaanngguuaaggee ddooeess nnoott
ssuuppppoorrtt EExxcceeppttiioonn hhaannddlliinngg ??
1. Java
2. C++
3. C

Q4. Which of tthheessee ssttaatteemmeennttss iiss ccoorrrreecctt ??
1. Try 3. Try
{ throw; { throw
}; };
2. Try 4. Try
{ throw; { throw
} }

Q5. WWhhiicchh ooff tthheessee ssttaatteemmeennttss iiss nnoott
ccoorrrreecctt ??
1. Catch(….){}
2. Catch(…){}
3. Catch(const char *message){}
4. Catch(int message){}

Exception handling

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