自定义的string类出错解决思路

自定义的string类出错
对 = 和 + 重载时；
class MyString
{
private:
int len;
char* c_MyString;
public:
MyString(int n);
~MyString();
void Getchar();
void Showstring();
bool operator == (const MyString &string);
bool operator != (const MyString &string);
bool operator > (const MyString &string);
bool operator < (const MyString &string);
MyString &operator + (const MyString &string);
MyString &operator = (const MyString &string);
char& operator [] (int n);
};

MyString &MyString::operator + (const MyString &string)
{
MyString a_MyString(100);
int i, n = len + string.len;
a_MyString.len = len + string.len;
char* ptr = a_MyString.c_MyString;
char* ptr1 = string.c_MyString;
char* ptr2 = c_MyString;
for(i = 1; i <= n; i ++)
{
if(i > len)
*ptr++ = *ptr2++;
else
*ptr++ = *ptr1++;
}
return a_MyString;
}

MyString &MyString::operator = (const MyString &string)
{

int n = string.len;
len = n;
delete [] c_MyString;
char* ptr = c_MyString;
char* ptr1 = string.c_MyString;
while(n--)
*ptr++ = *ptr1++;
return *this;
}
执行 s1 = s2 + s3 时出错，高手指点。

[解决办法]

C/C++ code

class MyString{    size_t m_len;public:    char* m_data;public:    MyString(const char* otherChar = NULL);    MyString(const string& other);    MyString(const MyString& other);    ~MyString();public:    MyString& operator =(const MyString& other);    friend MyString operator +(const MyString& str1, const MyString& str2);};//默认参数可作无参数构造函数使用MyString::MyString(const char* otherChar): m_len(strlen(otherChar)), m_data(new char[m_len + 1]){    if (otherChar == NULL)    {        *m_data = '\0';    }    else    {        for (size_t i=0; i<m_len+1; ++i)        {            m_data[i] = otherChar[i];        }    }}//我们的这个 string 类要支持 string 对象MyString::MyString(const string& other): m_len(other.size()), m_data(new char[m_len + 1]){    if (other.size() == 0)    {        *m_data = '\0';    }    else    {        for (size_t i=0; i<m_len+1; ++i)        {            m_data[i] = other.c_str()[i];        }    }}//拷贝构造函数MyString::MyString(const MyString& other): m_len(other.m_len), m_data(new char[other.m_len + 1]){    if (other.m_len == 0)    {        *m_data = '\0';    }    else    {        for (size_t i=0; i<m_len+1; ++i)        {            m_data[i] = other.m_data[i];        }    }}//敬爱的析构函数，总是扫尾MyString::~MyString(){    delete[] m_data;}//赋值操作符重载MyString& MyString::operator =(const MyString &other){    //自赋值检测    if (this == &other)    {        return *this;    }    //只有源对象和目标对象的长度不等时才重新分配空间    if (m_len != other.m_len)    {        m_len = other.m_len;        delete[] m_data;        m_data = new char[m_len + 1];    }    for (size_t i=0; i<m_len; ++i)    {        m_data[i] = other.m_data[i];    }    return *this;}//字符串相加，外部友元函数MyString operator +(const MyString& str1,                    const MyString& str2){    char* temp = new char[str1.m_len + str2.m_len + 1];    //忽略掉str1末尾的'\0'    for (size_t i=0; i<str1.m_len; ++i)    {        temp[i] = str1.m_data[i];    }    for (size_t j=0; j<str2.m_len+1; ++j)    {        temp[str1.m_len+j+1] = str2.m_data[j];    }    //return MyString(temp)        //这样不行，temp 的资源未释放掉    //没办法，新建立一个临时对象把 temp 的资源传递给它    MyString strTemp(temp);    //然后释放掉 temp 的资源    delete[] temp;    //对象 strTemp 的生命期到这里结束，会自动调用析构函数释放掉堆空间，不用担心内存泄漏啦    return strTemp;}