Question

我收到错误“表达式必须具有指向类的指针”。我已经搜索了错误并且无法找到一个我可以弄清楚发生了什么的帖子。我在第49行（data->resize( capacity * 2 );）

上收到Sequence2.cpp上的错误

Sequence2.h

typedef double value_type;

    class sequence
    {

    private:
        value_type* data;
        int used;
        int current_index;
        int capacity;

    public:
        // TYPEDEFS and MEMBER CONSTANTS
        static const int DEFAULT_CAPACITY = 5;

        // CONSTRUCTORS and DESTRUCTOR
        sequence(int initial_capacity = DEFAULT_CAPACITY);
        sequence(const sequence& source);
        ~sequence();

        // MODIFICATION MEMBER FUNCTIONS
        void insert(const value_type& entry);
        void resize(int new_capacity);

        // ADDITIONAL FUNCTIONS THAT ARE NOT RELEVANT

Sequence2.cpp

#include "stdafx.h"
#include "Sequence2.h"


//     Postcondition: The sequence has been initialized as an empty sequence.
//     The insert/attach functions will work efficiently (without allocating
//     new memory) until this capacity is reached.

sequence::sequence(int initial_capacity)
{
    capacity = initial_capacity;
    current_index = -1;
    data = new value_type[DEFAULT_CAPACITY];
}

sequence::sequence(const sequence & source)
{
    // NEED TO DO
    // Postcondition: the sequence has made a deep copy of the source sequence.
}

sequence::~sequence()
{
    delete[] data;
}

// Postcondition: A new copy of entry has been inserted in the sequence
// before the current item. If there was no current item, then the new entry 
// has been inserted at the front of the sequence. In either case, the newly
// inserted item is now the current item of the sequence.

void sequence::insert(const value_type & entry)
{
    if (current_index < 0) 
    {
        current_index = 0; // Set current index to first index
        data[current_index] = entry;
        used++;
    }
    else 
    {
        if (used < capacity) {
            data[current_index + 1] = entry;
            current_index++;
            used++;
        }
        else 
        {
            data->resize( capacity * 2 );
        }
    }


}



void sequence::resize(int new_capacity)
{
    value_type *temp = new value_type[capacity];
    int temp_capacity = capacity;

    for (int i = 0; i < capacity; i++)
    {
        temp[i] = data[i];
    }

    delete[] data;

    data = new value_type[new_capacity];

    for (int i = 0; i < temp_capacity; i++)
    {
        data[i] = temp[i];
        used++;
        current_index++;
    }

    delete[] temp;

}

Answer 1

resize也是会员功能，您没有正确调用它。变化

data->resize( capacity * 2 );

到

resize( capacity * 2 );

此处还有其他一些问题：

您可能需要在resize()中调用insert()后插入值。
new中无需delete / resize()两次。
used之后current_index和resize()的值似乎有误。

接收错误：表达式必须具有指向类的类型

1 个答案: