9. try與catch

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try與catch的機制，可以讓我們在try的程式區塊中，throw結果給catch區塊處理，請參考下面的程式：

using namespace std;
#include <iostream>
#include <cmath>
 
int main ()
{
   int a, b;
 
   cout << "Type a number: ";
   cin >> a;
   cout << endl;
 
   try
   {
      if (a > 100) throw 100;
      if (a < 10)  throw 10;
      throw a / 3;
   }
   catch (int result)
   {
      cout << "Result is: " << result << endl;
      b = result + 1;
   }
 
   cout << "b contains: " << b << endl;
 
   cout << endl;
 
   // another example of exception use:
 
   char zero []     = "zero";
   char pair []     = "pair";
   char notprime [] = "not prime";
   char prime []    = "prime";
 
   try
   {
      if (a == 0) throw zero;
      if ((a / 2) * 2 == a) throw pair;
      for (int i = 3; i <= sqrt (a); i++)
      {
         if ((a / i) * i == a) throw notprime;
      }
      throw prime;
   }
   catch (char *conclusion)
   {
      cout << "The number you typed is "<< conclusion << endl;
   }
 
   cout << endl;
 
   return 0;
}