1

I am trying to use the exceptions catching mechanism on a simple piece of C++ code that does on purpose a division by 0:

#include <iostream>
using namespace std;
const int DefaultSize = 10;

int main()
{
int top = 90;
int bottom = 0;
cout << "top / 2 = " << (top/ 2) << endl;
cout << "top / 3 = " << (top/ 3) << endl;

try
{
cout << "top divided by bottom = ";
cout << (top / bottom) << endl;
}
catch(...)
{
cout << "something has gone wrong!" << endl;
}
cout << "Done." << endl;
return 0;
}

The program crashes and doesn't execute the catch block - In Eclipse I am getting a standard error:
0 [main] CPP166 8964 cygwin_exception::open_stackdumpfile: Dumping stack trace to CPP166.exe.stackdump. Run the program in another IDE NetBeans and have done multiple clen and re-built with no positive results. Please help I have looked at the related answers but I cannot identify the problem.

paisanco
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user3404441
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1 Answers1

2

Division by zero is not one of the events that raises an exception in C++.

The exceptions listed in the ISO standard are:

namespace std {
    class logic_error;
        class domain_error;
        class invalid_argument;
        class length_error;
        class out_of_range;
    class runtime_error;
        class range_error;
        class overflow_error;
        class underflow_error;
}

and you would think that overflow_error would be ideal for indicating a divide by zero.

But C++03 and C++11 section 5.6 /4 specifically state:

If the second operand of / or % is zero, the behavior is undefined.

If you want an exception, you will have to code it yourself, with something like:

#include <stdexcept>

inline int intDiv (int num, int denom) {
    if (denom == 0) throw std::overflow_error("DivByZero");
    return num / denom;
}

and convert your calls from:

cout << (top / bottom) << endl;

to:

cout << intDiv(top, bottom) << endl;
paxdiablo
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