c++ - 错误: request for member . ..是非类类型的

Question

我意识到错误是由于在自定义类中使用 vector 而引起的，但是我一直在努力解决这些问题。当 vector 方法作为类对象的一部分时，如何调用它？

这些是我得到的错误:

Word.cpp: In member function ‘void Word::addPosition(int)’:
Word.cpp:20: error: request for member ‘push_back’ in ‘((Word*)this)->Word::positions’, which is of non-class type ‘std::vector<int, std::allocator<int> >*’
Word.cpp: In member function ‘int Word::getPosition(int)’:
Word.cpp:26: error: request for member ‘size’ in ‘((Word*)this)->Word::positions’, which is of non-class type ‘std::vector<int, std::allocator<int> >*’
Word.cpp:27: error: request for member ‘size’ in ‘((Word*)this)->Word::positions’, which is of non-class type ‘std::vector<int, std::allocator<int> >*’
Word.cpp:29: error: cannot convert ‘std::vector<int, std::allocator<int> >’ to ‘int’ in return

header

#pragma once
#include <string>
#include <vector>

class Word {
  public:
    Word();
    ~Word();
    void setWord(std::string);
    void addPosition(int);
    std::string getWord();
    int getPosition(int);
  private:
    std::string word;
    std::vector<int> *positions;
};

执行

#include "Word.h"
#include <string>
#include <vector>

Word::Word() {
    this->word = "";
    this->positions = new std::vector<int>(5);
}

void Word::setWord(std::string s) {
    this->word = s;
}

void Word::addPosition(int i) {
    this->positions.push_back(i);
}

std::string Word::getWord() {
    return this->word;
}

int Word::getPosition(int i) {
    if (i < this->positions.size() && i > 0) {
        for (int j = 0; j < this->positions.size(); i++) {
            if (i == j) {
                return positions[j];
            }
        }
    }
    return -1;
}

编辑:这是建立类(class)的更好方法吗？
header :

    #pragma once
    #include <string>
    #include <vector>

    class Word {
      public:
        Word();
        ~Word();
        void setWord(std::string);
        void addPosition(int);
        std::string getWord();
        int getPosition(int);
      private:
        std::string word;
        std::vector<int> positions;
    };

执行:

Word::Word(){
    word = "";
}

void Word::setWord(std::string s){
    this -> word = s;
}
void Word::addPosition(int i){
    this -> positions.push_back(i);
}
std::string Word::getWord(){
    return this -> word;
}
int Word::getPosition(int i){
    if (i < this -> positions.size() && i > 0) {
        for (int j = 0; j<this -> positions.size(); i++) {
            if (i == j) {
                return (this->positions)[j];
            }
        }
    }
    return -1;
}

但是现在我得到这个错误:

Undefined symbols for architecture x86_64:
  "_main", referenced from:
      start in crt1.10.6.o
ld: symbol(s) not found for architecture x86_64
collect2: ld returned 1 exit status

Answer 1

positions是一个指针。您需要取消引用它才能到达基本 vector :
this->positions->size();
通常，您遇到的错误是由于取消引用失败引起的(因为T*不是类类型；它是指针，而指针是原始类型)。