C++構造函數的異常說明符

Question

如何爲類構造函數編寫異常說明符。 在下面的例子中，throw（）可以正常工作，除了構造函數以外的所有其他成員函數。 我使用的是g ++ 4.8。

#include <exception> 
#include <string> 

class ArrayStackException: public std::exception { 
public: 
    ArrayStackException(std::string msg) : mMsg(msg) {} 
    virtual const char* what() const throw() { 
     return mMsg.c_str(); 
    } 
    std::string mMsg; 
}; 

template<typename T> 
class ArrayStack { 
public: 
    //ArrayStack() = delete; 
    explicit ArrayStack(int stackSize) throw(); 
    ~ArrayStack(); 
    void Push(T item) throw(); 
    T Pop() throw(); 
    bool IsEmpty() const; 
    T StackTop() const throw(); 

private: 
    int mStackSize; 
    int mTop; 
    T* mItems; 
}; 

template<typename T> 
ArrayStack<T>::ArrayStack(int stackSize) : mStackSize(stackSize), 
                 mTop(-1), 
                 mItems(nullptr) throw() { 
    if(stackSize < 1) { 
     throw ArrayStackException(std::string("Stack size must be geater than 0")); 
    } 

    mItems = new T[mStackSize]; 
} 

template<typename T> 
ArrayStack<T>::~ArrayStack() { 
    delete mItems; 
} 

template<typename T> 
void ArrayStack<T>::Push(T item) throw(){ 
    if(mTop == (mStackSize - 1)){ 
     throw ArrayStackException(std::string("Stack Overflow Occured...")); 
    } 

    ++mTop; 
    mItems[mTop] = item; 
} 

template<typename T> 
T ArrayStack<T>::Pop() throw(){ 
    if(IsEmpty() == true){ 
     throw ArrayStackException(std::string("Stack Underflow Occured...")); 
    } 

    return mItems[mTop--]; 
} 

template<typename T> 
bool ArrayStack<T>::IsEmpty() const { 
    return (mTop == -1 ? true : false); 
} 

template<typename T> 
T ArrayStack<T>::StackTop() const throw(){ 
    if(IsEmpty() == true) { 
     throw ArrayStackException(std::string("Stack is empty!!")); 
    } 

    return mItems[mTop]; 
} 



01:27:54 **** Incremental Build of configuration Debug for project ArrayStack **** 
make all 
Building file: ../src/ArrayStack.cpp 
Invoking: GCC C++ Compiler 
g++ -D__GXX_EXPERIMENTAL_CXX0X__ -O0 -g3 -Wall -c -fmessage-length=0 -std=c++11 -MMD -MP -MF"src/ArrayStack.d" -MT"src/ArrayStack.d" -o "src/ArrayStack.o" "../src/ArrayStack.cpp" 
In file included from ../src/ArrayStack.cpp:10:0: 
../src/ArrayStack.h:31:40: error: declaration of ‘ArrayStack<T>::ArrayStack(int)’ has a different exception specifier 
ArrayStack<T>::ArrayStack(int stackSize) : mStackSize(stackSize), 
             ^
../src/ArrayStack.h:17:11: error: from previous declaration ‘ArrayStack<T>::ArrayStack(int) throw()’ 
    explicit ArrayStack(int stackSize) throw(); 
     ^
../src/ArrayStack.h: In constructor ‘ArrayStack<T>::ArrayStack(int)’: 
../src/ArrayStack.h:33:33: error: expected ‘{’ before ‘throw’ 
       mItems(nullptr) throw() { 
           ^
../src/ArrayStack.h: At global scope: 
../src/ArrayStack.h:33:33: error: expected unqualified-id before ‘throw’ 
make: *** [src/ArrayStack.o] Error 1 

Answer 1

您在構造函數定義的錯誤位置有異常說明符。它應該在參數列表之後，而不是在成員初始化列表之後。

template<typename T> 
ArrayStack<T>::ArrayStack(int stackSize) throw() 
//         Here ^^^^^ 
: mStackSize(stackSize), mTop(-1), mItems(nullptr) {