Question

我刚开始使用c ++，因此我无法找到错误所在的位置。当我的代码到达通话assignGate时，它就会停止工作。我尝试删除了一行程序，一切正常。所以这个问题最有可能出现在那个函数中，但我看不出它有什么问题。

#include "stdafx.h"
#include <stdio.h>
#include <iostream>
#include <string>
#include <fstream>
using namespace std;

struct node {
    string code;
    int flight;
    int time; 
    string gate; 
    node *next; 
};

bool isEmpty(node *head);
void insert(node *&head, node *&last, string code, int flight, int time);
void remove(node *&head, node *&last);
void assignGate(node *&head, int gates);
void print(node *&head);

int main()
{
    int gates; 
    bool x = false;
    string code;
    int flight, time, gate; 
    node *head = NULL;
    node *last = NULL;
    cout << "Welcome to Gate Scheduler.\n";
    ifstream file("FlightList.txt");
    if (!file) {
        cout << "Unable to open text file. \n";
        cout << "Make sure file is in correct location then restart program. \n";
    }
    while (file >> code >> flight >> time) {
        insert(head, last, code, flight, time);
    }
    cout << "Please enter the max number of gates avaliable:";
        cin >> gates;
        assignGate(head, gates);
        cout << "\n";
    print(head);
    return 0;
}

bool isEmpty(node *head) {
    if (head == NULL) {
        return true;
    }
    else {
        return false;
    }
}

void insert(node *&head, node *&last, string code, int flight, int time) {
    node *temp = new node;
    temp->flight = flight;
    temp->code = code;
    temp->time = time;
    temp->next = NULL;
    if (isEmpty(head)) {
        head = temp;
        last = temp;
    }
    else {
        last->next = temp;
        last = temp;
    }
}

void remove(node *&head, node *&last) {
    if (isEmpty(head)) {
        cout << "The list is already empty \n";
    }
    else if (head == last) {
        delete head;
        head = NULL;
        last = NULL;
    }
    else {
        node *temp = head;
        head = head->next;
        delete temp;
    }
}

void assignGate(node *&head, int gates) {
    int y = 0;
    int gate[6];
    node* temp = head;
    while (temp->next != NULL) {
        if (temp->time > 2300 || temp->time < 600) {
            temp->gate = "N/A: Plane lands outside of airport operating hours.";
        }
        else {
            for (y = 0; y <= gates; ++y) {
                if (gate[y] == NULL) {
                    temp->gate = y;
                }
                else if (gate[y] + 100 < temp->time) {
                    temp->gate = y;
                }
            }
            if (temp->gate != "0" || "1" || "2" || "3" || "4") {
                temp->gate == "All gate are full at this time";
            }
        }
    }
}

void print(node *&head) {
    node* temp = head; 
    while (temp->next != NULL) {
        cout << "Flight " << temp->code << " " << temp->flight << " will be at gate " << temp->gate << "\n";
        temp = temp->next; 
    }

}

Answer 1

首先，您假设该数组初始化为零。它不是。您在gate []中没有零。你应该对它进行初始化以使它们为零。

 int gate[6] = {};

你真的应该检查门是否小于阵列的大小。

接下来，您的问题出在这一部分：

        else if (gate[y] + 100 < temp->time) {
                temp->gate = y;
            }
        }
        if (temp->gate != "0" || "1" || "2" || "3" || "4") {
            temp->gate == "All gate are full at this time";

temp->gate = y没有按你的想法行事。它将字符串分配给存储在整数中的代码。当然，if（）会失败。但它也会因为你写错了操作而失败。 (temp->gate != "0" || "1" || "2" || "3" || "4")等于... (temp->gate != true)您应该查看运营商优先级表以了解原因。

并且存在算法错误..你永远不会继续使用temp ..它保持不变，你永远不会从while循环中退出。

可能还有其他遗漏，因为它们对当前问题不是必不可少的。我专注于assignGate函数

PS。这不是错误，但风格非常糟糕：

bool isEmpty(node *head) {
    if (head == NULL) {
        return true;
    }
    else {
        return false;
    }
}

'head == NULL'是一个bool表达式。你可以退货。

inline bool isEmpty(node *head) {
   return head == NULL;
}

C ++程序在函数调用时停止

1 个答案: