C++ 关于一个成员函数的实现问题

Question

/*CArray是我写的、能够运行的、利用类来实现动态创建数组的工程，现在要加一个成员函数，要求如上，我把我理解的操作都写了下来，但我的疑问是在第一个判断条件中，函数返回要怎么写，是要跳过这个函数吗？除了这点，我下面写的实现过程有错吗？在main函数中能够输出对象obj1 resize后的数组吗？请大神们多多指教~*/

#include <iostream>
using namespace std;

class CArray{
public:CArray(unsigned int length=0);     
public:
    void print();
    void set();
    void resize(unsigned int length=0);
private:
    double *m_data;
    unsigned int m_nLength;
};

void CArray::resize(unsigned int length)
{
    if(length==m_nLength)
    //函数返回要怎么写？？

    else
    delete []m_data;
    if(length==0)
    m_data=NULL;
    else
    m_data=new double[length];
    m_nLength=length;
    cout<<"请输入"<<m_nLength<<"个数：";
    unsigned int i;
    for(i=0;i<m_nLength;i++)
        cin>>m_data[i];

}
CArray::CArray(unsigned int length)
{
    m_nLength=length;
    if( length==0)
    m_data=NULL;
    else
        m_data=new double[length];
}

void CArray::set()
{
    if( m_nLength==0)
    m_data=NULL;
    cout<<"请输入"<<m_nLength<<"个数：";
    for(unsigned int i=0;i<m_nLength;i++)
        cin>>m_data[i];
}


void CArray::print()
{
    if( m_nLength==0)
    m_data=NULL;
        unsigned int index;
        for(index=0;index<m_nLength;index++)
                cout<<m_data[index]<<" ";
}


        int main(int argc, char* argv[])
{
        unsigned int size;
        cout<<"请输入数组长度:";
        cin>>size;
        CArray obj(size);
            obj.set();
        cout<<"输入的数组为：";
        obj.print();

        CArray obj1;
        obj1.resize(3);
        obj1.print();
        return 0;
}

Answer 1

别的函数写的没问题，感觉你应该多个if判断

 void CArray::resize(unsigned int length)
{
    if(length==m_nLength)
        return;
    if(m_nLength > 0)//是否创建了动态数组
        delete []m_data;//先删除原来的数组

    if(length==0)
        m_data=NULL;
    else
        m_data=new double[length];
    m_nLength=length;
    cout<<"请输入"<<m_nLength<<"个数：";
    unsigned int i;
    for(i=0;i<m_nLength;i++)
        cin>>m_data[i];

}