c ++错误:只能指定限定符

Question

我不完全确定为什么会产生这个错误:

const class MyString {
public:
MyString() { _len = 0; _str = NULL; }
MyString(const char* in);
MyString(const MyString&);
~MyString();

int set(const char*);
int set(const MyString&);

int setLength(int len) { _len = len; return 0; }
int getLength() { return _len; }

char * getStr() { return _str; }
int getStr(char* out) const;

MyString operator+(const MyString & in);
MyString operator+(const char* in);
MyString operator+(const char in) {const char* temp = ∈ return *this + temp; }

MyString operator=(const MyString & in)
    { this->set(in); return *this; }
MyString operator=(const char* in)
    { if(in) this->set(in); return *this; }
MyString operator=(const char in) {const char* temp = ∈ return *this = temp; }

MyString operator+=(const MyString & in)
    { this->set(*this + in); return *this; }
MyString operator+=(const char* in)
    { if(in) this->set(*this + in); return *this; }
MyString operator+=(const char in) { return (*this + in); }

int operator==(const MyString& in);
int operator!=(const MyString& in);
int operator==(const char* in);
int operator!=(const char* in);

friend ostream& operator<<(ostream& os, const MyString & in)
    { os << in._str; return os; }

protected:
char * _str;
int _len;
};

错误是在最后一行生成的.该定义之前唯一的代码是'standard'#includes和using namespace std.

Answer 1

您发布的错误消息不完整,但没关系.

长话短说:删除const类声明最顶部的限定符,即class关键字之前的限定符.您只能const / volatile在变量或方法上添加cv-qualifiers().