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string类的实现:
class String
{
public:
String(const char *str=null);
String(const String &other);
~String();
String &operator =(const String &other);
String &operator +(const String &other);
bool operator ==(const String &other);
int getLength();
private:
char *m_data;
}
//普通构造函数
String::String(const char *str)
{
if(str == null)
{
m_data = new char[1];
*m_data = '\0';
}
else
{
int length = strlen(str);
m_data = new char[length + 1];
strcpy(m_data, str);
}
}
//析构函数
String::~String()
{
if(m_data)
{
delete[] m_data;
m_data=0;
}
}
//拷贝构造函数
String::String(const String &other)
{
if(!other.m_data)
{
m_data=0;
}
m_data = new char[strlen(other.m_data)+1];
strcpy(m_data, other.m_data);
}
//赋值函数
String& String::operator =(const String &other)
{
if(this != &other)
{
delete[] m_data;
if(!other.m_data)
{
m_data = 0;
}
else
{
m_data = new char[strlen(other.m_data)+1];
strcpy(m_data, other.m_data);
}
}
return *this;
}
//字符串连接
String &String::operator+(const String &other)
{
String newString;
if(!other.m_data)
{
newString = *this;
}
else if(!m_data)
{
newString = other;
}
else
{
newString.m_data = new char[strlen(m_data)+strlen(other.m_data)+1];
strcpy(newString.m_data, m_data);
strcat(newString.m_data, other.m_data);
}
return newString;
}
//判断相等
bool String::operator ==(const String &other)
{
if(strlen(m_data) != strlen(other.m_data))
{
return false;
}
else
{
return strcmp(m_data, other.m_data)?false:true;
}
}
//返回长度
int String::getLength()
{
return strlen(m_data);
}