Question

using namespace std;

struct WebSites
{
    string siteName;
    int rank;

    string getSiteName() { return siteName; }
    int getRank() { return rank; }
    WebSites(string const&, int);
    WebSites();
};

WebSites::WebSites(string const& siteName, int rank) {
    this->siteName = siteName;
    this->rank = rank;

}

WebSites::WebSites() {}

ostream& operator << (ostream& stream, WebSites const& data) {
    stream << data.rank << " " << data.siteName.size() << " " << data.siteName<< endl;
    return stream;

}

istream& operator >> (istream& stream, WebSites data) {
    stream >> data.siteName >> data.rank;
    return stream;

}


int main() {

    WebSites s1("www.google.co.uk", 1);

    //write to file

    ofstream writer("chou.dat", ios::out | ios::binary); //i'll add ios::app later
    if (!writer) {
        cout << " error opening file " << endl;
        return -1;
    }
    else {
        writer << s1.getSiteName() << " " << s1.getRank() << endl;
    }
    writer.close();

    //read file
    fstream writerR("chou.dat", ios::binary | ios::in | ios::ate);
    WebSites read;
    while (writerR >> read) {

        cout << read.siteName << " rank: "<< read.rank << endl;
    }
    writerR.close();
    return 0;
}

有人可以告诉我为什么这个程序不会读取并显示来控制文件???我的意思是写得很完美。我尝试改变东西，但没有任何效果我在线检查了类似的代码，但仍然没有。

Answer 1

有一些问题：

同意docs指定ios::ate

在打开后立即寻找流的结尾

所以没有什么可读的，你的while循环永远不会被输入。
另一个问题是：operator >> (istream& stream, WebSites data)

您的运营商正在使用数据填写副本。要解决这个第二个参数应该是一个参考：

operator >> (istream& stream, WebSites& data)

C ++文件I / O我无法读取.dat文件

1 个答案: