Terminate called after throwing an instance of an exception, core dumped












11














I am going over C++ exceptions and am running into an error that I am unsure of why it is giving me issues:



 #include <iostream>
#include <exception>

class err : public std::exception
{
public:
const char* what() const noexcept { return "error"; }
};

void f() throw()
{
throw err();
}

int main()
{
try
{
f();
}
catch (const err& e)
{
std::cout << e.what() << std::endl;
}
}


When I run it, I get the following runtime error:



 terminate called after throwing an instance of 'err'
what(): error
Aborted (core dumped)


If I move the try/catch logic completely to f(), i.e.



 void f() 
{
try
{
throw err();
}
catch (const err& e)
{
std::cout << e.what() << std::endl;
}
}


And just call it from main (without the try/catch block in main), then there is no error. Am I not understanding something, as it relates to throwing exceptions from functions?










share|improve this question




















  • 9




    void f() throw() says that the function doesn't throw exceptions. And then you do.
    – Neil Butterworth
    Jan 2 at 18:42






  • 2




    Remove the throw(). You are saying "this function never throws" but then you violate that promise and throw anyway. That leads to std::terminate since you broke the rules of the language - at that point you cannot expect anything.
    – Jesper Juhl
    Jan 2 at 18:57


















11














I am going over C++ exceptions and am running into an error that I am unsure of why it is giving me issues:



 #include <iostream>
#include <exception>

class err : public std::exception
{
public:
const char* what() const noexcept { return "error"; }
};

void f() throw()
{
throw err();
}

int main()
{
try
{
f();
}
catch (const err& e)
{
std::cout << e.what() << std::endl;
}
}


When I run it, I get the following runtime error:



 terminate called after throwing an instance of 'err'
what(): error
Aborted (core dumped)


If I move the try/catch logic completely to f(), i.e.



 void f() 
{
try
{
throw err();
}
catch (const err& e)
{
std::cout << e.what() << std::endl;
}
}


And just call it from main (without the try/catch block in main), then there is no error. Am I not understanding something, as it relates to throwing exceptions from functions?










share|improve this question




















  • 9




    void f() throw() says that the function doesn't throw exceptions. And then you do.
    – Neil Butterworth
    Jan 2 at 18:42






  • 2




    Remove the throw(). You are saying "this function never throws" but then you violate that promise and throw anyway. That leads to std::terminate since you broke the rules of the language - at that point you cannot expect anything.
    – Jesper Juhl
    Jan 2 at 18:57
















11












11








11







I am going over C++ exceptions and am running into an error that I am unsure of why it is giving me issues:



 #include <iostream>
#include <exception>

class err : public std::exception
{
public:
const char* what() const noexcept { return "error"; }
};

void f() throw()
{
throw err();
}

int main()
{
try
{
f();
}
catch (const err& e)
{
std::cout << e.what() << std::endl;
}
}


When I run it, I get the following runtime error:



 terminate called after throwing an instance of 'err'
what(): error
Aborted (core dumped)


If I move the try/catch logic completely to f(), i.e.



 void f() 
{
try
{
throw err();
}
catch (const err& e)
{
std::cout << e.what() << std::endl;
}
}


And just call it from main (without the try/catch block in main), then there is no error. Am I not understanding something, as it relates to throwing exceptions from functions?










share|improve this question















I am going over C++ exceptions and am running into an error that I am unsure of why it is giving me issues:



 #include <iostream>
#include <exception>

class err : public std::exception
{
public:
const char* what() const noexcept { return "error"; }
};

void f() throw()
{
throw err();
}

int main()
{
try
{
f();
}
catch (const err& e)
{
std::cout << e.what() << std::endl;
}
}


When I run it, I get the following runtime error:



 terminate called after throwing an instance of 'err'
what(): error
Aborted (core dumped)


If I move the try/catch logic completely to f(), i.e.



 void f() 
{
try
{
throw err();
}
catch (const err& e)
{
std::cout << e.what() << std::endl;
}
}


And just call it from main (without the try/catch block in main), then there is no error. Am I not understanding something, as it relates to throwing exceptions from functions?







c++ c++11 exception






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Jan 2 at 18:48









Ron

10.5k21834




10.5k21834










asked Jan 2 at 18:40









HectorJ

675




675








  • 9




    void f() throw() says that the function doesn't throw exceptions. And then you do.
    – Neil Butterworth
    Jan 2 at 18:42






  • 2




    Remove the throw(). You are saying "this function never throws" but then you violate that promise and throw anyway. That leads to std::terminate since you broke the rules of the language - at that point you cannot expect anything.
    – Jesper Juhl
    Jan 2 at 18:57
















  • 9




    void f() throw() says that the function doesn't throw exceptions. And then you do.
    – Neil Butterworth
    Jan 2 at 18:42






  • 2




    Remove the throw(). You are saying "this function never throws" but then you violate that promise and throw anyway. That leads to std::terminate since you broke the rules of the language - at that point you cannot expect anything.
    – Jesper Juhl
    Jan 2 at 18:57










9




9




void f() throw() says that the function doesn't throw exceptions. And then you do.
– Neil Butterworth
Jan 2 at 18:42




void f() throw() says that the function doesn't throw exceptions. And then you do.
– Neil Butterworth
Jan 2 at 18:42




2




2




Remove the throw(). You are saying "this function never throws" but then you violate that promise and throw anyway. That leads to std::terminate since you broke the rules of the language - at that point you cannot expect anything.
– Jesper Juhl
Jan 2 at 18:57






Remove the throw(). You are saying "this function never throws" but then you violate that promise and throw anyway. That leads to std::terminate since you broke the rules of the language - at that point you cannot expect anything.
– Jesper Juhl
Jan 2 at 18:57














1 Answer
1






active

oldest

votes


















16














The throw() in void f() throw() is a dynamic exception specification and is deprecated since c++11. It's was supposed to be used to list the exceptions a function could throw. An empty specification (throw()) means there are no exceptions that your function could throw. Trying to throw an exception from such a function calls std::unexpected which, by default, terminates.



Since c++11 the preferred way of specifying that a function cannot throw is to use noexcept. For example void f() noexcept.






share|improve this answer























  • Thank you! I had an incorrect understanding. It looks like noexcept(false) will provide the same functionality and looks to not have been deprecated
    – HectorJ
    Jan 2 at 18:59






  • 4




    @HectorJ noexcept(false) is the default for most functions and usually does not need to be provided. I believe destructors are noexcept(true) by default and as far as I know that would be the only time noexcept(false) has meaning (though that's not recommended).
    – François Andrieux
    Jan 2 at 19:00













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1 Answer
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active

oldest

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oldest

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active

oldest

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16














The throw() in void f() throw() is a dynamic exception specification and is deprecated since c++11. It's was supposed to be used to list the exceptions a function could throw. An empty specification (throw()) means there are no exceptions that your function could throw. Trying to throw an exception from such a function calls std::unexpected which, by default, terminates.



Since c++11 the preferred way of specifying that a function cannot throw is to use noexcept. For example void f() noexcept.






share|improve this answer























  • Thank you! I had an incorrect understanding. It looks like noexcept(false) will provide the same functionality and looks to not have been deprecated
    – HectorJ
    Jan 2 at 18:59






  • 4




    @HectorJ noexcept(false) is the default for most functions and usually does not need to be provided. I believe destructors are noexcept(true) by default and as far as I know that would be the only time noexcept(false) has meaning (though that's not recommended).
    – François Andrieux
    Jan 2 at 19:00


















16














The throw() in void f() throw() is a dynamic exception specification and is deprecated since c++11. It's was supposed to be used to list the exceptions a function could throw. An empty specification (throw()) means there are no exceptions that your function could throw. Trying to throw an exception from such a function calls std::unexpected which, by default, terminates.



Since c++11 the preferred way of specifying that a function cannot throw is to use noexcept. For example void f() noexcept.






share|improve this answer























  • Thank you! I had an incorrect understanding. It looks like noexcept(false) will provide the same functionality and looks to not have been deprecated
    – HectorJ
    Jan 2 at 18:59






  • 4




    @HectorJ noexcept(false) is the default for most functions and usually does not need to be provided. I believe destructors are noexcept(true) by default and as far as I know that would be the only time noexcept(false) has meaning (though that's not recommended).
    – François Andrieux
    Jan 2 at 19:00
















16












16








16






The throw() in void f() throw() is a dynamic exception specification and is deprecated since c++11. It's was supposed to be used to list the exceptions a function could throw. An empty specification (throw()) means there are no exceptions that your function could throw. Trying to throw an exception from such a function calls std::unexpected which, by default, terminates.



Since c++11 the preferred way of specifying that a function cannot throw is to use noexcept. For example void f() noexcept.






share|improve this answer














The throw() in void f() throw() is a dynamic exception specification and is deprecated since c++11. It's was supposed to be used to list the exceptions a function could throw. An empty specification (throw()) means there are no exceptions that your function could throw. Trying to throw an exception from such a function calls std::unexpected which, by default, terminates.



Since c++11 the preferred way of specifying that a function cannot throw is to use noexcept. For example void f() noexcept.







share|improve this answer














share|improve this answer



share|improve this answer








edited Jan 2 at 18:59

























answered Jan 2 at 18:44









François Andrieux

15.4k32647




15.4k32647












  • Thank you! I had an incorrect understanding. It looks like noexcept(false) will provide the same functionality and looks to not have been deprecated
    – HectorJ
    Jan 2 at 18:59






  • 4




    @HectorJ noexcept(false) is the default for most functions and usually does not need to be provided. I believe destructors are noexcept(true) by default and as far as I know that would be the only time noexcept(false) has meaning (though that's not recommended).
    – François Andrieux
    Jan 2 at 19:00




















  • Thank you! I had an incorrect understanding. It looks like noexcept(false) will provide the same functionality and looks to not have been deprecated
    – HectorJ
    Jan 2 at 18:59






  • 4




    @HectorJ noexcept(false) is the default for most functions and usually does not need to be provided. I believe destructors are noexcept(true) by default and as far as I know that would be the only time noexcept(false) has meaning (though that's not recommended).
    – François Andrieux
    Jan 2 at 19:00


















Thank you! I had an incorrect understanding. It looks like noexcept(false) will provide the same functionality and looks to not have been deprecated
– HectorJ
Jan 2 at 18:59




Thank you! I had an incorrect understanding. It looks like noexcept(false) will provide the same functionality and looks to not have been deprecated
– HectorJ
Jan 2 at 18:59




4




4




@HectorJ noexcept(false) is the default for most functions and usually does not need to be provided. I believe destructors are noexcept(true) by default and as far as I know that would be the only time noexcept(false) has meaning (though that's not recommended).
– François Andrieux
Jan 2 at 19:00






@HectorJ noexcept(false) is the default for most functions and usually does not need to be provided. I believe destructors are noexcept(true) by default and as far as I know that would be the only time noexcept(false) has meaning (though that's not recommended).
– François Andrieux
Jan 2 at 19:00




















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