VSCode not catching a thrown exception?

Asked May 01 '21 at 12:53

Active May 01 '21 at 13:00

Viewed 145 times

I'm still learning C++ and I'm trying to implement exception handling using a try-catch block.

#include<iostream>
#include<cstdlib> //for exit
const int divide_flag(-1);
double divide(double x, double y){
  if(x==0) throw divide_flag;
  return y/x;
}
int main()
{
  double x{3.},y{4.};
  double result;
  try{
    result=divide(x,y);
    std::cout<<"y/x = "<<result<<std::endl;
    x=0;
    result=divide(x,y);
    std::cout<<"y/x = "<<result<<std::endl;
  }
  catch(int error_flag) {
    if(error_flag == divide_flag) {
      std::cerr<<"Error: divide by zero"<<std::endl;
      exit(error_flag);
    }
  }
  return 0;
}

The code compiles fine but when I run it the program aborts after the exception is thrown and does not enter the catch block. The only output I get is

y/x = 1.33333
Abort trap: 6

I'm compiling with g++ on Mac and I'm not sure why the catch block is never entered.

edited May 01 '21 at 12:56

πάντα ῥεῖ

asked May 01 '21 at 12:53

Archie

@churill Well, and that's caused by a never (unlikely) true condition: `if(x==0)`? – πάντα ῥεῖ May 01 '21 at 12:58
I don't think the floating point Q's answer this, since zero is a value where exact comparison will work. – aschepler May 01 '21 at 12:59
Okey ... reopened – πάντα ῥεῖ May 01 '21 at 13:00
What compiler are you using? With gcc 9.3.0 I get your "Error: divide by zero" line. – aschepler May 01 '21 at 13:02
`exit(error_flag);` should be `std::exit(error_flag);`. The `` may not necessarily have `exit` in the global namespace. (It doesn't on my machine.) – Eljay May 01 '21 at 13:50
Adding std::exit didn't work, and I'm using gcc 8 – Archie May 01 '21 at 14:10

VSCode not catching a thrown exception?

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