大家好！我用C++写了一个简单的矩阵类，用函数返回矩阵的长度和宽度时，得到长度正确，但有些对象的宽度正确，而另一些对象的宽度却错误，且VS没有报错。因为部分宽度正确，部分却不正确，我真的搞不懂问题出在哪。恳请大家指点，谢谢！

我的代码由三个头文件(模板类)和main组成，同时我也将代码放在了百度网盘，下载地址为：http://pan.baidu.com/s/1eQg8Sgi，谢谢！

dynamicVector.h

#pragma once

#include<stdio.h>

template<class T> class dynamicVector
{
protected:
    int dimension;    // dimension of the dynamic vector (元素的个数);
    T* component;    // point to the components of the vector （指针数组）;

public:
    // dynamicVector( );
    dynamicVector( int, const T& );
    dynamicVector( const dynamicVector& );

    // 符号重载；
    const dynamicVector& operator=( const dynamicVector& );
    const dynamicVector& operator=( const T& );

    const dynamicVector& operator+=( const dynamicVector& );
    const dynamicVector& operator-=( const dynamicVector& );
    const dynamicVector& operator*=( const T& );
    const dynamicVector& operator/=( const T& );


    ~dynamicVector()
    {
        delete [] component;
    } // destructor


    int dim() const
    {
        return dimension;
    }    // return the demension;

    T& operator() ( int i )
    {
        return component[i];
    }    // read/write ith component;

    const T& operator[] ( int i ) const
    {
        return component[i];
    }    // read only ith component;
    
};

/*
template<class T>
dynamicVector<T> ::dynamicVector()
{
    dimension = 1;
    component = new T[dimension];
}    // default constructor;
*/

template<class T>
dynamicVector<T> ::dynamicVector( int dim = 1, const T& a = 0 )
    : dimension( dim ), component( dim ? new T[dim] : 0 )    // 类成员变量初始化；
{
    for (int i = 0; i < dim; i++)
    {
        component[i] = a;
    }
}    // constructor;


template<class T>
dynamicVector<T>::dynamicVector( const dynamicVector<T>& v )
    : dimension( v.dimension ), component( v.dimension ? new T[v.dimension] : 0 )
{
    for (int i = 0; i < v.dimension; i++)
    {
        component[i] = v.component[i];
    }
} // copy constructor；


// 重载‘=’，vector = vector
template<class T>
const dynamicVector<T>&
dynamicVector<T>::operator=( const dynamicVector<T>& v )
{
    if (this != &v)    // 避免赋值给本身；
    {
        if (dimension > v.dimension)    // 当前 vector 的维数大于 v 的维数；
        {
            delete[]( component + v.dimension );    // 删除多余的空间；
        }

        if (dimension < v.dimension)
        {
            delete[] component;
            component = new T[v.dimension];
        }

        for (int i = 0; i < v.dimension; i++)    // 当两者维数相同时，对应元素赋值；
        {
            component[i] = v.component[i];
        }

        dimension = v.dimension;
    }

    return *this;
} // assignment operator


// 重载符号‘=’，vector[i] = a
template<class T>
const dynamicVector<T>&
dynamicVector<T>::operator=( const T& a )
{
    for (int i = 0; i < dimension; i++)
    {
        component[i] = a;
    }

    return *this;
} // assignment operator with a scalar argument


// 重载符号‘+=’，vectorA = vectorA + vectorB
template<class T>
const dynamicVector<T>&
dynamicVector<T>::operator+=( const dynamicVector<T>& v )
{
    for (int i = 0; i < dimension; i++)
    {
        component[i] += v[i];
    }

    return *this;
}// adding a dynamicVector to the current one


// 重载‘-=’
template<class T>
const dynamicVector<T>&
dynamicVector<T>::operator-=( const dynamicVector<T>&v )
{
    for (int i = 0; i < dimension; i++)
    {
        component[i] -= v[i];
    }
    return *this;
} // subtract a dynamicVector from the current one


// 重载‘*=’
template<class T>
const dynamicVector<T>&
dynamicVector<T>::operator*=( const T& a )
{
    for (int i = 0; i < dimension; i++)
    {
        component[i] *= a;
    }
    return *this;
} // multiply the current dynamicVector by a scalar


// 重载‘/=’
template<class T>
const dynamicVector<T>&
dynamicVector<T>::operator/=( const T& a )
{
    for (int i = 0; i < dimension; i++)
    {
        component[i] /= a;
    }
    return *this;
} // pide the current dynamicVector by a scalar


// 重载符号‘+’，vectorC = vectorA + vectorB
template<class T>
const dynamicVector<T>
operator+( const dynamicVector<T>& u, const dynamicVector<T>& v )
{
    return dynamicVector<T>( u ) += v;
} // dynamicVector plus dynamicVector


// 重载符号‘-’，vectorA = vectorA * -1.0;
template<class T>
const dynamicVector<T>
operator-( const dynamicVector<T>& u )
{
    return dynamicVector<T>( u ) *= -1.0;
} // negative of a dynamicVector


// 重载‘-’
template<class T>
const dynamicVector<T>
operator-( const dynamicVector<T>&u, const dynamicVector<T>&v )
{
    return dynamicVector<T>( u ) -= v;
} // dynamicVector minus dynamicVector


// 重载‘*’
template<class T>
const dynamicVector<T>
operator*( const dynamicVector<T>&u, const T& a )
{
    return dynamicVector<T>( u ) *= a;
} // dynamicVector times scalar


// 重载‘*’
template<class T>
const dynamicVector<T>
operator*( const T& a, const dynamicVector<T>&u )
{
    return dynamicVector<T>( u ) *= a;
} // T times dynamicVector


// 重载‘*’
template<class T>
T operator*( const dynamicVector<T>&u, const dynamicVector<T>&v )
{
    T sum = 0;
    for (int i = 0; i < u.dim(); i++)
    {
        sum += u[i] * +v[i];
    }

    return sum;
} // inner product


// 重载‘/’
template<class T>
const dynamicVector<T>
operator/( const dynamicVector<T>&u, const T& a )
{
    return dynamicVector<T>( u ) /= a;
} // dynamicVector pided by scalar


// print vector;
template<class T>
void printOut( const dynamicVector<T>& v )
{
    //print( "(" );
    std::cout << "( ";
    for (int i = 0; i < v.dim(); i++)
    {
        //printf( "v[%d]=", i );
        //print( v[i] );
        std::cout << v[i] << " ";
    }

    //print( ")\n" );
    std::cout << " )" << std::endl;
    
} // printing a dynamicVector


/*
template<class T>
void writeOut( dynamicVector<T>& v, const char& txtName )
{
    ofstream writeTxt( txtName, ios::out );//供写，文件不存在则创建，若文件已存在则清空原内容(ofstream默认的打开方式);

    writeTxt << "( ";
    for (int i = 0; i < l.size(); i++)
    {
        writeTxt << v[i] << " ";
    }
    writeTxt << " )" << std::endl;

} // write a list in to txt
*/

list.h

    #pragma once

#include <stdio.h>
#include <iostream>
#include <fstream> 
#include <sstream> 

template<class T> class list
{
protected:
    int number;    // the number of items; list中单元(dynamic vector)的个数
    T** item;    //  "item" to store their addresses. 指针的指针，指向指针数组中的指针(地址)；

public:
    list( int n = 0 ) :number( n ), item( n ? new T*[n] : 0 )
    {

    } // constructor
    

    list( int n, const T& t )
        : number( n ), item( n ? new T*[n] : 0 )
    {
        for (int i = 0; i < number; i++)
        {
            item[i] = new T( t );
        }
            
    } // constructor with T argument
    

    list( const list<T>& );    //  copy constructor
    const list<T>& operator=( const list<T>& );    // 重载‘=’；


    ~list()
    {
        for (int i = 0; i < number; i++)
        {
            delete item[i];    // deletes first the pointers in the array in the "list" object
        }
            
        delete[] item;    //  then the entire array itself:
    } // destructor；


    // accessing the size of the list (number of items);
    const int size()
    {
        return number;
    } // list size


    // accessing items by overriding '()' and '[]';
    T& operator()( int i )
    {
        if (item[i])
        {
            return *( item[i] );
        }
    } // read/write ith item


    const T& operator[]( int i ) const    // 'const' means read only;
    {
        if (item[i])
        {
            return *( item[i] );
        }
    } // read only ith item
};


template<class T>
list<T>::list( const list<T>& l ) :number( l.number ), item( l.number ? new T*[l.number] : 0 )
{
    for (int i = 0; i < l.number; i++)
    {
        if (l.item[i])
        {
            item[i] = new T( *l.item[i] );
        }
    }
        
} // copy constructor


template<class T>
const list<T>&
list<T>::operator=( const list<T>& l )
{
    if (this != & l)    // 避免赋值给自身；
    {
        // make sure that the current list contains
        // the same number of items as the list ’l’ that is passed as an argument        
        if (number > l.number)
        {
            delete[]( item + l.number );
        }

        if (number < l.number)
        {
            delete[] item;
            item = new T*[l.number];
        }

        for (int i = 0; i < l.number; i++)
        {
            if (l.item[i])
            {
                item[i] = new T( *l.item[i] );
            }
        }
            
        number = l.number;
    }

    return *this;
} // assignment operator


template<class T>
void printOut( const list<T>& l )
{
    for (int i = 0; i < l.size(); i++)
    {
        //printf( "i=%d:\n", i );
        //print( l[i] );
        std::cout << "i= " << i << std::endl;
        // std::cout << l[i] << std::endl;
        printOut(l[i]);
    }
} // printing a list



template<class T>
void writeOut( const list<T>& l, char* txtName )
{
    std::ofstream writeTxt( txtName, std::ios::app );//供写，文件不存在则创建，若文件已存在则清空原内容(ofstream默认的打开方式);
    
    for (int i = 0; i < l.size(); i++)
    {    
        writeTxt << "i= " << i << std::endl;
        writeTxt << l[i] << std::endl;
    }
} // write a list in to txt

dynamicMatrix.h

#pragma once
#include <algorithm>
#include "dynamicVector.h"
#include "list.h"


template<class T>   //  "dynamicMatrix" class 存放系数矩阵；
class dynamicMatrix : public list < dynamicVector<T> >        // derived from list < dynamicVector<T> >;
{
public:
    dynamicMatrix();
    dynamicMatrix( int m, int n, const T& ); // constructor;

    // 符号重载；
    const dynamicMatrix<T>& operator+=( const dynamicMatrix<T>& );
    const dynamicMatrix<T>& operator-=( const dynamicMatrix<T>& );
    const dynamicMatrix& operator*=( const T& );
    //const dynamicMatrix<T>& operator=( const dynamicMatrix<T>& );    // 重载‘=’；


    //  'operators()' allow one to refer to the elements D j,j − 1 ,
    // D j,j , and D j,j + 1 simply as "D(j,j-1)", "D(j,j)", and "D(j,j+1)", respectively.
    T& operator()( int i, int j )
    {
        return ( *item[i] )( j );
    } // (i,j)th element (read/write)


    //  the read-only version of 'operator()'
    const T& operator()( int i, int j, char* ) const    // 'const' for reading only;
    {
        return ( *item[i] )[j];
    } // (i,j)th element (read only)


    //  返回vector中元素的个数，列数；
    int width() const
    {
        return item[0]->dim();
    } // width of grid

    // 返回list中vector的个数，行数；
    int lenght() const
    {
        return number;
    }
};

template<class T>
dynamicMatrix<T>::dynamicMatrix()
{
    number = 1;    // number继承自list基类，此处表示dynamicVector的个数，即item的个数；                                                                

    item = new dynamicVector<T>*[1];    // 设置dynamicVector中元素的个数；

    for (int i = 0; i < number; i++)
    {
        item[i] = new dynamicVector<T>( 1, T(0.0) );
    }
}



// constructor，形成一个(m*n)的矩阵；
template<class T>
dynamicMatrix<T>::dynamicMatrix( int m = 1, int n = 1, const T& a = 0 )    //  m为行数, n为列数；
{
    number = m;    // number继承自list基类，此处表示dynamicVector的个数；                                                                

    item = new dynamicVector<T>*[n];    // 设置dynamicVector中元素的个数；
    
    for (int i = 0; i < number; i++)
    {
        item[i] = new dynamicVector<T>( n, a );
    }

    // std::cout << m << " " << n << std::endl;

} // constructor


// 重载‘+=’
template<class T>
const dynamicMatrix<T>& dynamicMatrix<T>::operator+=( const dynamicMatrix<T>& d )
{
    for (int i = 0; i < number; i++)
    {
        *item[i] += d[i];
    }

    return *this;

} // adding another "dynamicMatrix" to the current one


// 重载‘-=’
template<class T>
const dynamicMatrix<T>& dynamicMatrix<T>::operator-=( const dynamicMatrix<T>& d )
{
    for (int i = 0; i < number; i++)
    {
        *item[i] -= d[i];
    }

    return *this;

} // subtracting a "dynamicMatrix" from the current one


// 重载‘*=’
template<class T>
const dynamicMatrix<T>& dynamicMatrix<T>::operator*=( const T& t )
{
    for (int i = 0; i < size(); i++)
    {
        *item[i] *= t;
    }

    return *this;

} // multiplying the current "dynamicMatrix" by a scalar T


// 重载‘+’
template<class T>
const dynamicMatrix<T> operator+( const dynamicMatrix<T>& d1, const dynamicMatrix<T>& d2 )
{
    return dynamicMatrix<T>( d1 ) += d2;
} // adding two "dynamicMatrix" objects


// 重载‘-’
template<class T>
const dynamicMatrix<T> operator-( const dynamicMatrix<T>& d1, const dynamicMatrix<T>& d2 )
{
    return dynamicMatrix<T>( d1 ) -= d2;
} // subtracting two "dynamicMatrix" objects


// 重载‘*’
template<class T>
const dynamicMatrix<T> operator*( const T& t, const dynamicMatrix<T>& d )
{
    return dynamicMatrix<T>( d ) *= t;
} // scalar times "dynamicMatrix"


// 重载‘*’
template<class T>
const dynamicMatrix<T> operator*( const dynamicMatrix<T>& d, const T& t )
{
    return dynamicMatrix<T>( d ) *= t;
} // "dynamicMatrix" times scalar


// 重载‘*’
template<class T>
const dynamicVector<T> operator*( const dynamicMatrix<T>& d, const dynamicVector<T>& v )
{
    dynamicVector<T> dv( v.dim(), 0. );

    for (int i = 0; i < v.dim(); i++)
    {
        for (int j = std::max( 0, i - 1 ); j <= std::min( v.dim() - 1, i + 1 ); j++)
        {
            dv( i ) += d( i, j, "read" )*v[j];
        }
    }

    return dv;
} // "dynamicMatrix" times vector


template<class T>
void printOut( const dynamicMatrix<T>& m )
{
    for (int i = 0; i < m.lenght(); i++ )
    {
        printOut( m[i] );
    }
}

main.cpp

#include "dynamicMatrix.h"


int main()
{
    const int volumeNumX = 5;
    const int volumeNumY = 7;


    std::cout << "It's OK-2!" << std::endl;
    dynamicMatrix<double> geoCoeMatrix( volumeNumX*volumeNumY, volumeNumX*volumeNumY, 0.0 );

    dynamicMatrix<double> geoCoeRHS( volumeNumX*volumeNumY, 1, 0.0 );

    dynamicMatrix<double> initRootDens( volumeNumX*volumeNumY, 1, 0.0 );
    dynamicMatrix<double> rootDens( volumeNumX*volumeNumY, 1, 0.0 );

    //std::cout << volumeNumX << " " << volumeNumY << std::endl;
    std::cout << geoCoeMatrix.lenght() << " " << geoCoeMatrix.width() << std::endl;
    std::cout << geoCoeRHS.lenght() << " " << geoCoeRHS.width() << std::endl;
    std::cout << initRootDens.lenght() << " " << initRootDens.width() << std::endl;
    std::cout << rootDens.lenght() << " " << rootDens.width() << std::endl;

    std::cin.get();

    return 0;
}