http://blog.csdn.net/wangshihui512/article/details/9792309

已知String類聲明如下：

[cpp]?view plaincopy print?

class?String???

{???

????public:???

????String(const?char?*str?=?NULL);?//?通用構造函數???

????String(const?String?&another);?//?拷貝構造函數???

????~?String();?//?析構函數???

????String?&?operater?=(const?String?&rhs);?//?賦值函數???

????private:???

????char?*m_data;?//?用于保存字符串???

};???

寫出類的成員函數實現：

[cpp]?view plaincopy print?

String::String(const?char?*str)???

{???

????if?(?str?==?NULL?)?//strlen在參數為NULL時會拋異常才會有這步判斷???

????{???

????????m_data?=?new?char[1]?;???

????????m_data[0]?=?'\0'?;???

????}???

????else???

????{???

????????m_data?=?new?char[strlen(str)?+?1];???

????????strcpy(m_data,str);???

????}???

}???

String::String(const?String?&another)???

{???

????m_data?=?new?char[strlen(another.m_data)?+?1];???

????strcpy(m_data,other.m_data);???

}???

String&?String::operator?=(const?String?&rhs)???

{???

????if?(?this?==?&rhs)???

????????return?*this?;???

????delete?[]m_data;?//刪除原來的數據，新開一塊內存???

????m_data?=?new?char[strlen(rhs.m_data)?+?1];???

????strcpy(m_data,rhs.m_data);???

????return?*this?;???

}???

String::~String()???

{???

????delete?[]m_data?;???

}???

String::String(const char *str)?
{?
??? if ( str == NULL ) //strlen在參數為NULL時會拋異常才會有這步判斷?
??? {?
??????? m_data = new char[1] ;?
??????? m_data[0] = '\0' ;?
??? }?
??? else?
??? {?
??????? m_data = new char[strlen(str) + 1];?
??????? strcpy(m_data,str);?
??? }?
}?
String::String(const String &another)?
{?
??? m_data = new char[strlen(another.m_data) + 1];?
??? strcpy(m_data,other.m_data);?
}?
String& String::operator =(const String &rhs)?
{?
??? if ( this == &rhs)?
??????? return *this ;?
??? delete []m_data; //刪除原來的數據，新開一塊內存?
??? m_data = new char[strlen(rhs.m_data) + 1];?
??? strcpy(m_data,rhs.m_data);?
??? return *this ;?
}?
String::~String()?
{?
??? delete []m_data ;?
}?

總結

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