c++ - 搜索并行数组

Question

我的程序旨在从包含标题和作者列表的文件中获取输入。该文件如下所示:

titleassociated authornext titleassociated authoretc.

The problem I'm having is with my showBooksByTitle and showBooksByAuthor functions. Right now this code returns only exact matches and also prints an empty newline and a new line with some spaces and a ().

Of course any help is greatly appreciated. This is my first year programming. I've included the whole code just to be safe that I'm not leaving out anything that could be the problem.

#include <iostream>
#include<string>
#include<fstream>
#include<cstring>

using namespace std;

struct Book {
    string title;
    string author;
};

const int ARRAY_SIZE = 1000;
Book books [ARRAY_SIZE];

int loadData (string);
void showAll (int);
int showBooksByAuthor (int, string);
int showBooksByTitle (int, string);

int main() {
    //Declare variables
    string pathname;
    string title;
    string name;
    string word;
    int count;
    char response;

    //ask user for pathname
    cout << "What is the path of the library file? ";
    cin >> pathname;
    cout << endl;
    count = loadData(pathname);

    //input data into arrays
    loadData(pathname);
    cout << endl << count << " records loaded successfully." << endl << endl;

    //Show user menu
    cout << "Please enter Q to Quit, A to search for the Author, T to search for the Title, "
    << endl << "or S to Show all: ";
    cin >> response;

    switch(response) {
        case 'q':
            break;
        case 'Q':
            break;
        case 'a':
            cout << endl << "Please enter author's name: ";
            cin >> name;
            showBooksByAuthor(count, name);
            break;
        case 'A':
            cout << endl << "Please enter author's name: ";
            cin >> name;
            showBooksByAuthor(count, name);
            break;
        case 't':
            cout << endl << "Please enter all or part of the title: ";
            cin >> title;
            showBooksByTitle(count, title);
            break;
        case 'T':
            cout << endl << "Please enter all or part of the title: ";
            cin >> title;
            showBooksByTitle(count, title);
            break;
        case 's':
            cout << endl;
            showAll(count);
            break;
        case 'S':
            cout << endl;
            showAll(count);
            break;
        default:
            cout << endl << "Invaled input, please try again: ";
            break;
    }

    //pause and exit
    cout << endl;
    system("PAUSE");
    return 0;
}


int loadData(string pathname) {
    int i = 0;
    int j = 0;
    ifstream library;

    //open file, if not successful, output error message
    library.open(pathname.c_str());
    if (!library.is_open()) {
        cout << "Unable to open input file." << endl;
        return -1;
    }
    //reads title and author from file into designated string
    //this is assuming title comes first and author comes after
    while(!library.eof()) {
        getline(library, books[i].title);
        getline(library, books[i].author);
        i++;
    }
    return i;
}

void showAll (int count) {
    for (int i = 0; i < count; i++) {
        cout << books[i].title << " (" << books[i].author << ")" << endl;
    }
}

int showBooksByAuthor(int count, string name) {
    int found;
    for(int n = 0; n < 28; n++) {
        found = name.find(books[n].author);
        if(found != string::npos) {
            cout << endl << books[n].title << " (" << books[n].author << ")" << endl;
        }
    }
    return 0;
}


int showBooksByTitle (int count, string title) {
    int found;
    for(int n = 0; n < 28; n++) {
        found = title.find(books[n].title);
        if(found !=string::npos) {
            cout << endl << books[n].title << " (" << books[n].author << ")" << endl;
        }
    }
    return 0;
}

Answer 1

意外的输出是因为你读错了数据文件。流 EOF 标志不会设置，直到您尝试对流执行操作后，因此您的循环迭代一到多次。

将 loadData 中的循环更改为:

while(getline(library, books[i].title) && getline(library, books[i].author))
    i++;

这利用了 std::getline 返回流的事实，并且流可以用作 true/false 值。