Question

我的类Row在bitset中包含其数据。该类是使用模板实现的，但是在主程序中无法创建Row对象的新实例。

Row.h

#ifndef ROW_H_
#define ROW_H_

#include <bitset>

template <std::size_t N>
class Row {

public:
    typedef std::bitset<N> bs;

private:
    Row::bs *data;

public:
    Row();                          // ctor
    Row(const Row::bs&);
    Row(const Row&);                // copy construktor
    Row<N>& operator=(const Row&);  // copy with '='
    virtual ~Row();                 // dtor

    // compare
    bool operator==(const Row&) const;
    bool operator!=(const Row&) const;
    bool operator<(const Row&) const;
    bool operator>(const Row&) const;

    // setter
    void reset();                               // set all bits to 0
    void set();                                 // set all bits to 1
    //void set(std::size_t, bool val = true);   // set bit at position npos to 0 or 1
    void set(const Row::bs&);                   // set with another bitset

    // getter
    std::size_t size() const;   // number of bits
    std::size_t count() const;  // number of bits that are set on 1
    bool any() const;           // true if any bit is set on 1
    bool none() const;          // true if no bit is set on 1
    //Row::bs& getData;
    //const Row::bs& getData() const;

    // to stream
    virtual void toStream(std::ostream&) const;
    friend std::ostream& operator<<(std::ostream&, const Row&);
};

#endif /* ROW_H_ */

Row.cpp

#include "Row.h"
// ------------------------- ctor dtor -------------------------
template <std::size_t N>
Row<N>::Row() : data(new Row::bs()) {}

template <std::size_t N>
Row<N>::Row(const Row::bs& bits) : data(new Row::bs(bits)) {}

template <std::size_t N>
Row<N>::Row(const Row& r) { this->data = new Row::bs(r.getData()); }

template <std::size_t N>
Row<N>& Row<N>::operator=(const Row& r) {
    if( this != &r ) { // self assignment ?
        delete this->data; this->data=0;
        this->set( r.getData() );
    }
    return *this;
}

template <std::size_t N>
Row<N>::~Row() {
    if(this->data) { delete this->data; } this->data=0;
}


// ------------------------- compare -------------------------
template <std::size_t N>
bool Row<N>::operator==(const Row& r) const {
    if( this->size() == r.size() ) return this->data & r.getData();
    else return false;
}

template <std::size_t N>
bool Row<N>::operator!=(const Row& r) const {
    return !( *this == r );
}

template <std::size_t N>
bool Row<N>::operator<(const Row& r) const {
    return this->size() < r.size();
}

template <std::size_t N>
bool Row<N>::operator>(const Row& r) const {
    return r < *this;
}


// ------------------------- setter -------------------------
template <std::size_t N>
void Row<N>::reset() { this->data->reset(); }

template <std::size_t N>
void Row<N>::set() { this->data->set(); }

/*template <std::size_t N>
void Row<N>::set(std::size_t npos, bool val = true) { this->data->set(npos,val); }*/

template <std::size_t N>
void Row<N>::set(const Row::bs& bits) { this->data = new Row::bs(bits); }


// ------------------------- getter -------------------------
template <std::size_t N>
std::size_t Row<N>::size() const { return N; }

template <std::size_t N>
std::size_t Row<N>::count() const { return this->data->count(); }

template <std::size_t N>
bool Row<N>::any() const { return this->data->any(); }

template <std::size_t N>
bool Row<N>::none() const { return this->data->none(); }

template <std::size_t N>
Row::bs& Row<N>::getData const { return *this->data; }

template <std::size_t N>
const Row::bs& Row<N>::getData() const { return *this->data; }


// ------------------------- to stream -------------------------
template <std::size_t N>
void Row<N>::toStream(std::ostream& os) const { os << this->data; } // should call    bitset<N>::to_string

std::ostream& operator<<(std::ostream& os, const Row& r) {
    r.toStream(os);
    return os;
}

main.cpp中：

#include "Row.h"

int main() {

    Row<4> *r1 = new Row();

    delete r1; r1=0;

    return 0;
}

编译器消息是德语...

In file included from ../Main.cpp:8:0:
../Row.h:54:59: Warnung: »friend«-Deklaration »std::ostream& operator<<(std::ostream&, const Row<N>&)« deklariert eine Nicht-Template-Funktion [-Wnon-template-friend]
../Row.h:54:59: Anmerkung: (wenn das nicht beabsichtigt war, sollte sicher gestellt werden, dass das Funktions-Template bereits deklariert wurde, und <> hier hinter Funktionsnamen eingefügt wurde) 
../Main.cpp: In Funktion »int main()«:
../Main.cpp:13:19: Fehler: expected type-specifier before »Row«
../Main.cpp:13:19: Fehler: »int*« kann nicht nach »Row<4ul>*« in Initialisierung umgewandelt werden
../Main.cpp:13:19: Fehler: expected »,« or »;« before »Row«


make: *** [Main.o] Fehler 1

但是以下事情失败了： - 在main中创建新实例 - 运算符＆lt;＆lt;输出 - getData（）方法

Answer 1

Row<4> *r1 = new Row();

应该是：

Row<4> *r1 = new Row<4>();

或者，更好，

Row<4> r1;

无法创建位行的实例

1 个答案: