1 Introduction

　　Exceptions are C ++ language standard library itself or thrown exception subclass called standard exceptions. Catch all standard exceptions statement:

the try {
     // may throw the exception 
} the catch (Exception & E) // references are used in order to improve efficiency, or to go through a process of copying the object. 
{ 
    // exception handling statements 
}

1.1 exception class

　　class located exception <exception> header file, is declared as:

class Exception {
 public : 
    Exception () the throw ();   // Constructor 
    Exception ( const Exception &) the throw ();   // copy constructor 
    Exception & operator = ( const Exception &) the throw ();   // operator overloading 
    Virtual ~ Exception () the throw ();   // virtual destructor 
    virtual  const  char * What () const  the throw ();   // virtual function 
}

　　what function returns a string that can identify anomalies, the programmer can tell this is anything unusual, but the C ++ standard does not specify the format of the string to achieve the various compiler is different, so what's the return value for reference only.

1.2 exception class inheritance hierarchy

1.2.1 exception of direct derived class

The exception name	Description
logic_error	logical error.
runtime_error	Run-time error.
bad_alloc	The use of new or new [] throws an exception when memory allocation fails.
bad_typeid	Typeid operation using a NULL pointer, and the pointer is a class with a virtual function, then bad_typeid thrown exception.
bad_cast	Use dynamic_cast conversion failed when thrown exception.
ios_base::failure	Io anomaly occurred during.
bad_exception	This is a special exception, if the function's exception list declares bad_exception exception when internal function throws an exception list is no exception, if you call the unexpected () function throws an exception, regardless of what type, will be replace bad_exception type.

1.2.2 logic_error derived class

The exception name	Description
length_error	Try to build out of the anomaly of an object exceeds the maximum length of this type, for example, the vector resize operation.
domain_error	Range parameter errors, mainly used in mathematical functions, such as using a negative function call can only operate non-negative.
out_of_range	It is out of range.
invalid_argument	Parameters inappropriate. In the standard library, when using the string object construction bitset, and the string of characters is not the time to 0 or 1, Thrown.

1.2.3 runtime_error derived class

The exception name	Description
range_error	The results exceeded the significant value range.
overflow_error	Arithmetic overflow.
underflow_error	Arithmetic underflow.

Standard C ++ base class exception: exception class