为什么我得到错误：初始化'Item :: Item（int）'[-fpermissive]在Eclipse中的参数1当我尝试编译我的C ++代码？ [英] Why am I getting error: initializing argument 1 of 'Item::Item(int)' [-fpermissive] in Eclipse when I try to compile my C++ code?

问题描述

我是C ++的新手，最终放弃了尝试让它编译后盯着它太久了。编译器似乎是在头文件中拒绝构造函数原型的某些原因...我不能弄清楚它的错误。

I'm new to C++, and have finally given up on trying to get this to compile after staring at it for too long. The compiler seems to be rejecting the constructor prototype in the header file for some reason... I can't figure out what's wrong with it.

Item.h：

#ifndef ITEM_H_
#define ITEM_H_


class Item {
public:
    Item(int); //This line is what Eclipse keeps flagging up with the error in the title
    virtual ~Item();
    Item* getNextPtr();
    int getValue();
    void setNextPtr(Item *);
};

#endif /* ITEM_H_ */

我有：

int val;
Item* nextPtr = 0;
Item::Item(int value) {
    val = value;
}

Item* Item::getNextPtr() {
    return nextPtr;
}

void Item::setNextPtr(Item *nextItem) {
    nextPtr = nextItem;
} 

int Item::getValue() {
    return val;
}

Item::~Item() {
    // TODO Auto-generated destructor stub
} 

糟糕，我使用的是GCC。是的，他们应该是成员变量！我该如何使用这种格式呢？我使用实例化项目的代码如下。我知道这里不应该有全局变量...

Oops, I'm using GCC. And yeah, they should have been member variables! How do I go about doing that using this format? The code where I use instantiate Item is below. I am aware that there should be no global variables in that either...

#include "LinkList.h"
#include "Item.h"

Item* first = 0;
int length = 0;

LinkList::LinkList(int values[], int size) {
    length = size;
    if (length > 0) {
        Item firstItem = new Item(values[0]);
        Item *prev = &firstItem;
        first = &firstItem;
        for (int i = 0; i < size; i++) {
            Item it = new Item(values[i]);
            prev->setNextPtr(&it);          //set 'next' pointer of previous item to current item
            prev = &it;                     // set the current item as the new previous item
        }

    }
}

LinkList::~LinkList() {
    for (int i = 0; i < length; i++) {
        Item firstItem = *first;
        Item *newFirst = firstItem.getNextPtr();
        delete(first);
        first = newFirst;
    }
}

int LinkList::pop() {
    Item firstItem = *first;
    first = firstItem.getNextPtr();
    return firstItem.getValue();
}

我刚刚注意到一个与pop析构函数...请忽略这些，我只想弄清楚Item的实例化有什么问题。

I've just noticed a bug with the functionality of the pop() and destructor functions... please ignore those, I just want to figure out what's wrong with the instantiation of Item.

GCC错误：

Info: Internal Builder is used for build
g++ -O0 -g3 -Wall -c -fmessage-length=0 -o "src\\LinkList.o" "..\\src\\LinkList.cpp" 
..\src\LinkList.cpp: In constructor 'LinkList::LinkList(int*, int)':
..\src\LinkList.cpp:16:38: error: invalid conversion from 'Item*' to 'int' [-fpermissive]
..\src\/Item.h:14:2: error:   initializing argument 1 of 'Item::Item(int)' [-fpermissive]
..\src\LinkList.cpp:20:32: error: invalid conversion from 'Item*' to 'int' [-fpermissive]
..\src\/Item.h:14:2: error:   initializing argument 1 of 'Item::Item(int)' [-fpermissive]

21:24:26 Build Finished (took 256ms)

推荐答案

这里：

Item firstItem = new Item(values[0]);

您正在创建一个项目指针作为其参数的新项目。这与：

You are creating a new Item with an item pointer as its argument. This is the same as:

Item firstItem(new Item(values[0]));

它应该是：

Item *firstItem = new Item(values[0]);

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