主页 / 问题 / 969632
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Григорий
Asked:2020-04-15 01:24:05 +0000 UTC2020-04-15 01:24:05 +0000 UTC

如何将类对象写入文件？

  • 772

如何对 I/O 进行编程？（最好是二进制形式）

using namespace System;
using namespace System::IO;

ref class test {
    String ^value1;
    String ^value2;
    int id;
    String ^value3;
public:
    test() { };
    test(String ^v1, String ^v2, String ^v3, int n) : value1(v1), value2(v2), value3(v3), id(n) { };

    int get_id() { return id; }
    void write_me(String ^path) {
    //.......... <<<< here
    }
    void read_me(String ^path) {
    //.......... <<<< here    
    }
};

int main() {
    test ^tst1("hello","cat", "biscuit", 3);
    tst1->write_me("write_test.dat");

    test ^tst2;
    tst2.read_me("write_test.dat");

    return 0;
}
c++-cli

1 个回答

  1. Best Answer

    如果有人需要：

    using namespace System;
using namespace System::IO;

#define endl "\n"

ref class test {
protected:
    String ^value1;
    String ^value2;
    String ^value3;
    int id;

    // поиск максимального id в записанных данных
    int get_counter(String ^path) {
        int max_counter = 0;
        BinaryReader ^br = gcnew BinaryReader(File::Open(path, FileMode::OpenOrCreate));
        while(br->BaseStream->Position != br->BaseStream->Length) {
            br->ReadString(); //читаем в той же последовательности как записывали
            br->ReadString();
            int current_id = br->ReadInt32(); // согласно типу значения
            br->ReadString();

            max_counter < current_id ? max_counter = current_id : max_counter = max_counter;
        }
        br->Close();
        return max_counter;
    }
public:
    test() { };
    test(String ^v1, String ^v2, String ^v3) : value1(v1), value2(v2), value3(v3) { };

    void write_me(String ^path) {
        id = get_counter(path) + 1;

        BinaryWriter ^bw = gcnew BinaryWriter(File::Open(path, FileMode::Append));
        bw->Write(value1);
        bw->Write(value2);
        bw->Write(id);
        bw->Write(value3);
        bw->Close();
    }
    void read_me(BinaryReader ^br) {
        value1 = br->ReadString();
        value2 = br->ReadString();
        id = br->ReadInt32();
        value3 = br->ReadString();
    }
    void print_me() {
        Console::WriteLine("id=" + id + endl + value1 + endl + value2 + endl + value3 + endl + endl);
    }
};


int main() {
    // WRITING
    for(int i = 0; i < 5; ++i) {
        test ^tst1 = gcnew test((i * 1).ToString(), (i * 2).ToString(), (i * 3).ToString());
        tst1->write_me("test.dat");
    }

    // READING
    BinaryReader ^br = gcnew BinaryReader(File::Open("test.dat", FileMode::Open));
    while(br->BaseStream->Position != br->BaseStream->Length) {
        test ^temp = gcnew test();
        temp->read_me(br);
        temp->print_me();
    }
    br->Close();

    Console::ReadKey();
    return 0;
}
    • 0

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