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A simple exception handling example
#include <iostream>
using namespace std;
int main()
{
cout << "Start\n";
try {
cout << "Inside try block\n";
throw 1; // throw an error
cout << "This will not execute";
}
catch (int i) { // catch an error
cout << "Caught an exception -- value is: ";
cout << i << "\n";
}
cout << "End";
return 0;
}Start
Inside try block
Caught an exception -- value is: 1
End"
A try block can be localized to a function
#include <iostream>
using namespace std;
void f(int test)
{
try{
if(test) throw test;
}
catch(int i) {
cout << "Caught One! Ex. #: " << i << "\n";
}
}
int main()
{
cout << "start\n";
f(1);
f(2);
f(0);
f(3);
cout << "end";
return 0;
}start
Caught One! Ex. #: 1
Caught One! Ex. #: 2
Caught One! Ex. #: 3
end
Catch all exceptions
#include <iostream>
using namespace std;
void f(int test)
{
try{
if(test==0) throw test; // throw int
if(test==1) throw "a"; // throw char
if(test==2) throw 123.23; // throw double
}
catch(...) { // catch all exceptions
cout << "Caught One!\n";
}
}
int main()
{
f(0);
f(1);
f(2);
return 0;
}Caught One!
Caught One!
Caught One!
Catch "char *" exception
#include <iostream.h>
int main () {
try
{
throw "Out of range";
}
catch (char * str)
{
cout << "Exception: " << str << endl;
}
return 0;
}This application has requested the Runtime to terminate it in an unusual way.
Please contact the application"s support team for more information.
Catching derived classes
#include <iostream>
using namespace std;
class B {
};
class D: public B {
};
int main()
{
D derived;
try {
throw derived;
}
catch(B b) {
cout << "Caught a base class.\n";
}
catch(D d) {
cout << "This won"t execute.\n";
}
return 0;
}Multiple catch blocks
#include <iostream.h>
int main () {
try
{
char * mystring;
mystring = new char [10];
if (mystring == NULL)
throw "Allocation failure";
for (int n=0; n<=100; n++)
{
if (n>9)
throw n;
mystring[n]="a";
}
}
catch (int i)
{
cout << "index " << i << " is out of range" << endl;
}
catch (char * str)
{
cout << "Exception: " << str << endl;
}
return 0;
}index 10 is out of range
Throwing an exception from a function called from within a try block
#include <iostream>
using namespace std;
void f(int test)
{
cout << "Inside f, test is: " << test << "\n";
if(test)
throw test;
}
int main()
{
cout << "start\n";
try { // start a try block
cout << "Inside try block\n";
f(0);
f(1);
f(2);
}
catch (int i) { // catch an error
cout << "Caught an exception -- value is: ";
cout << i << "\n";
}
cout << "end";
return 0;
}start
Inside try block
Inside f, test is: 0
Inside f, test is: 1
Caught an exception -- value is: 1
end
try catch block without exception being thrown
#include <iostream>
using namespace std;
int main()
{
cout << "Start\n";
try {
cout << "Inside try block\n";
cout << "Still inside try block\n";
}
catch (int i) {
cout << "Caught an exception -- value is: ";
cout << i << "\n";
}
cout << "End";
return 0;
}Start
Inside try block
Still inside try block
End"
Use catch(...) as a default
#include <iostream>
using namespace std;
void f(int val)
{
try{
if(val==0)
throw val;
if(val==1)
throw "a";
if(val==2)
throw 123.23;
}
catch(int i) { // catch an int exception
cout << "Caught an integer\n";
}
catch(...) { // catch all other exceptions
cout << "Caught One!\n";
}
}
int main()
{
f(0);
f(1);
f(2);
return 0;
}Caught an integer
Caught One!
Caught One!
Use multiple catch statements
#include <iostream>
using namespace std;
void f(int test)
{
try{
if(test)
throw test; // throw int
else
throw "Value is zero"; // throw char *
}
catch(int i) {
cout << "Caught One! Ex. #: " << i << "\n";
}
catch(char *str) {
cout << "Caught a string: ";
cout << str << "\n";
}
}
int main()
{
cout << "start\n";
f(1);
f(2);
f(0);
f(3);
cout << "end";
return 0;
}start
Caught One! Ex. #: 1
Caught One! Ex. #: 2
This application has requested the Runtime to terminate it in an unusual way.
Please contact the application"s support team for more information.
