异常处理开关：try{}catch（...）{}

try{}catch（...）{};这条语句在我们平时程序中会经常用到，当异常发生时能自动捕获。而对于程序异常时，我们可以通过参数

/EH{s|a}[c][-]

来设置要捕获对象。

Arguments

a

The exception-handling model that catches asynchronous (structured) and synchronous (C++) exceptions.

s

The exception-handling model that catches C++ exceptions only and tells the compiler to assume that extern C functions do throw an exception.

c

If used with s (/EHsc), catches C++ exceptions only and tells the compiler to assume that extern C functions never throw a C++ exception. /EHca is equivalent to /EHa.

Remarks

Use /EHs to specify the synchronous exception handling model (C++ exception handling without structured exception handling exceptions). If you use /EHs, then your catch clause will not catch asynchronous exceptions. Also, all objects in scope when the asynchronous exception is generated will not be destroyed even if the asynchronous exception is handled. Under /EHs, catch(...) will only catch C++ exceptions. Access violations and System.Exception exceptions will not be caught.

Use /EHa to specify the asynchronous exception handling model (C++ exception handling with structured exception handling exceptions). /EHa may result in a less performant image because the compiler will not optimize a try block as aggressively, even if the compiler does not see a throw.

Use /EHa if you want to catch an exception raised with something other than a throw. The following sample will generate an exception:

// compiler_options_EHA.cpp
// compile with: /EHa
#include <iostream>
#include <excpt.h>
using namespace std;

void fail() {   // generates SE and attempts to catch it using catch(...)
   try {
      int i = 0, j = 1;
      j /= i;   // This will throw a SE (divide by zero).
      printf("%d", j); 
   }
   catch(...) {   // catch block will only be executed under /EHa
      cout<<"Caught an exception in catch(...)."<<endl;
   }
}

int main() {
   __try {
      fail(); 
   }

   // __except will only catch an exception here
   __except(EXCEPTION_EXECUTE_HANDLER) {   
   // if the exception was not caught by the catch(...) inside fail()
      cout << "An exception was caught in __except." << endl;
   }
}

该开关位置：
VS2010中如下图