如何连续读取两次相同的文件 [英] How to read same file twice in a row

问题描述

我读一个文件一次，找到它包含的行数，然后再次读取它，所以我可以存储每一行​​的一些数据在一个数组。有没有更好的方式阅读文件两次，关闭和再次打开它？这是我得到的，但是害怕它是低效的。

I read through a file once to find the number of lines it contains then read through it again so I can store some data of each line in an array. Is there a better way to read through the file twice than closing and opening it again? Here is what I got but am afraid it's inefficient.

int numOfMappings = 0;
ifstream settingsFile("settings.txt");
string setting;
while(getline(settingsFile, setting))
{
    numOfMappings++;
}
char* mapping = new char[numOfMappings];
settingsFile.close();
cout << "numOfMappings: " << numOfMappings << endl;
settingsFile.open("settings.txt");
while(getline(settingsFile, setting))
{
    cout << "line: " << setting << endl;
}

推荐答案

settingsFile.clear();
settingsFile.seekg(0, settingsFile.beg);

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