C ++ eof（）问题 - 从不返回true？ [英] C++ eof() problem - never returns true?

问题描述

所以我想读这个文件。一切看起来像它应该工作，但在运行时程序超时并停止工作，我不得不关闭它。到底是怎么回事？我怀疑oef（）测试永远不会返回true，它一直在文件中寻找更多。我没有在文本文件中拖动空行。我试过调试这个疯了。我找不到任何错误，但仍然拒绝工作。

So I'm trying to read this file. Everything looks like it should work, but during runtime the program times out and stops working, and I have to close it. What is going on? I suspect that the oef() test is never returning true and it keeps looking for more in the file. I have no dragging empty lines in the text file. I've tried debugging this like crazy. I can't find anything wrong but it still refuses to work.

Pet** petArray;

ifstream textFile2;
textFile2.open("pets.txt");

int i = 0;
string temp;
int tmpNum = 0;

if (textFile2.is_open())
{
    while (!textFile2.eof())
    {

        getline(textFile2, temp);

        petArray = new Pet*[arraySize];

        if (temp == "Dogs" || temp == "Cats" || temp == "Iguanas" || temp == "Pigs")
        {
            if (temp == "Dogs") tmpNum = 0;
            if (temp == "Cats") tmpNum = 1;
            if (temp == "Iguanas") tmpNum = 2;
            if (temp == "Pigs") tmpNum = 3;
            temp == "";
        }
        else
        {
            if (tmpNum == 0)
            {
                petArray[i] = new Dog(temp);
                cout << "Dog " << temp << " added" << endl;
            }
            if (tmpNum == 1)
            {
                petArray[i] = new Cat(temp);
                cout << "Cat " << temp << " added" << endl;
            }
            if (tmpNum == 2)
            {
                petArray[i] = new Iguana(temp);
                cout << "Iguana " << temp << " added" << endl;
            }
            if (tmpNum == 3)
            {
                petArray[i] = new Pig(temp);
                cout << "Pig " << temp << " added" << endl;
            }
            arraySize++;
        }

        i++;
    }
}

这里是文本文件的格式：

Here is the format of the text file:

Dogs
d1
d2
Cats
c1
c2
Iguanas
i1
i2
Pigs
p1
p2

有任何建议吗？

推荐答案

eof 在 之后尝试读取某些内容，操作失败。因此，在 getline 后面输入。

eof returns true after you tried to read something and the operation failed. So put it after getline.

编辑：尝试此代码：

vector<Pet*> petArray;
ifstream textFile2("pets.txt");

string temp;
int tmpNum = 0;

while (getline(textFile2, temp))
{
    if (temp == "Dogs") tmpNum = 0;
    else if (temp == "Cats") tmpNum = 1;
    else if (temp == "Iguanas") tmpNum = 2;
    else if (temp == "Pigs") tmpNum = 3;
    else
    {
        if (tmpNum == 0)
        {
            petArray.push_back(new Dog(temp));
            cout << "Dog " << temp << " added" << endl;
        }
        if (tmpNum == 1)
        {
            petArray.push_back(new Cat(temp));
            cout << "Cat " << temp << " added" << endl;
        }
        if (tmpNum == 2)
        {
            petArray.push_back(new Iguana(temp));
            cout << "Iguana " << temp << " added" << endl;
        }
        if (tmpNum == 3)
        {
            petArray.push_back(new Pig(temp));
            cout << "Pig " << temp << " added" << endl;
        }
    }
}

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