Question

I have this simple try catch for throwing cin exceptions, but it never throws exceptions.

while(cin>>num) {
   try {
      if(cin.fail()) {
         throw "error";
      }
      if(num>0) {
        cout << "number greater than 0" << endl;
      }
   }
   catch(char* error) {
      cout << error << endl;
   }
}

Why it is not throwing the exception?

Answer 1

cin >> num return false, so your loop body doesn’t get executed at all.

If you really need to use execption

while(true)
{
    cin >> num;
    try{
       if(cin.fail()){
           throw "error";
       }
       if(num>0){
           cout<<"number greater than 0"<<endl;
       }
   }
   catch( char* error){
      cout<<error<<endl;
          break;
   }
}

It’s better to put the try catch outside of the loop to get better performance