类模板中的一个小问题 找不到原因??
应该把Negative index输出,可是为什么输出的是Index too large??????
#ifndef Array_H
#define Array_H
#include <stdexcept>
template <typename T> class Array{
private:
T* elements;
size_t size;
public:
explicit Array <T> (size_t arraySize);
Array <T> (const Array <T> & theArray);
~Array <T> ();
T& operator[](size_t index);
const T& operator[](size_t index) const;
Array <T> & operator=(const Array <T> & rhs);
};//类模板
template <typename T> Array <T> ::Array(size_t arraySize):size(arraySize){
elements=new T[size];
}//构造函数
template <typename T> Array <T> ::Array(const Array &theArray){
size=theArray.size;
elements=new T[size];
for(int i=0;i <size;i++)
elements[i]=theArray.elements[i];
}//副本构造函数
template <typename T> Array <T> ::~Array(){
delete[] elements;
}//析构函数
template <typename T> T& Array <T> ::operator [](size_t index){
if(index <0||index> =size)
throw std::out_of_range(index <0? "Negative index ": "Index too large ");
return elements[index];
}//重载下标运算符非const 类型
template <typename T> const T& Array <T> ::operator [](size_t index) const{
if(index <0||index> =size)
throw std::out_of_range(index <0? "Negative index ": "Index too large ");
return elements[index];
}//重载下标运算符 const 类型
template <typename T> Array <T> & Array <T> ::operator =(const Array& rhs){
if(this=&rhs)
return *this;
if(elements)
delete[] elements;
size=rhs.size;
elements=new T[size];
for(i=0;i <size;i++)
elements[i]=rhs.elements[i];
}//重载赋值运算符
#endif
_______________________________________Array.h___________________________
#ifndef Box_H
#define Box_H
class Box{
public:
double volume(double a=1,double b=1,double c=1);
private:
double a;
double b;
double c;
};
double Box::volume(double a,double b,double c)
{
return a*b*c;
}
#endif
_________________________________Box.h__________________________________
#include "Box.h "
#include "Array.h "
#include <iostream>
#include <iomanip>
using std::cout;
using std::endl;
int main()
{
const int doubleCount=50;
Array <double> values(doubleCount);
try{
for (int i=0;i <doubleCount;i++)
values[i]=i+1;
cout < <endl < < "Sums of pairs of elements; ";
int lines=0;
for(i=doubleCount-1;i> =0;i--)
cout < <(lines++ % 5==0? "\n ": " ") < <std::setw(5)
< <values[i]+values[i-1];
/*问题是当i为-1时调用 Arrary.h中template <typename T> T& Array <T> ::operator [](size_t index)重载[]函数 因为i=-1时下标越界要抛异常按throw std::out_of_range(index <0? "Negative index ": "Index too large ");这条语句应该把Negative index输出,可是为什么输出的是Index too large??????*/
}
catch(const std::out_of_range& ex){
cout < <endl < < "out_of_range exception object caught! " < <ex.what();
}
try{
const int boxCount=10;
Array <Box> boxes(boxCount);
for(int i=0;i <=boxCount;i++)
cout < <endl < < "Box volume is " < <boxes[i].volume();
}
catch(const std::out_of_range& ex){
cout < <endl < < "out_of_range exception object caught ! " < <ex.what();
}
cout < <endl;
return 0;
}
[解决办法]
size_t是无符号数！
