读取文本文件并以内存有效的方式搜索字符串(发现后中止) [英] read a text file and search for string in memory efficient way (and abort when found)

问题描述

我正在搜索文本文件(还包括XML)中的字符串.这是我首先想到的:

I'm searching for a string in a text file (also includes XML). This is what I thought first:

using (StreamReader sr = File.OpenText(fileName))
{
    string s = String.Empty;
    while ((s = sr.ReadLine()) != null)
    {
        if (s.Contains("mySpecialString"))
            return true;
    }
}

return false;

我想逐行读取以最小化RAM的使用量.找到字符串后，应中止该操作.我之所以不将其作为XML进行处理，是因为必须对其进行解析，并且在必要时还会消耗更多的内存.

I want to read line by line to minimize the amount of RAM used. When the string has been found it should abort the operation. The reason why I don't process it as XML is because it has to be parsed and would also consume more memory as necessary.

另一个容易实现的方法是

Another easy implementation would be

bool found = File.ReadAllText(path).Contains("mySpecialString") ? true : false;

但是这会将完整的文件读入内存，这不是我想要的.另一方面，它可能会提高性能.

but that would read the complete file into memory, which isn't what I want. On the other side it could have a performance increase.

另一个是这个

foreach (string line in File.ReadLines(path))
{
    if (line.Contains("mySpecialString"))
    {
        return true;
    }
}
return false;

但是其中哪一个(或您中的另一个?)的内存使用效率更高?

But which one of them (or another one from you?) is more memory efficient?

推荐答案

您可以将查询与

You can use a query with File.ReadLines, so it only reads as many lines as it needs to, in order to satisfy your query. The Any() method will stop when it hits a line containing your string.

return File.ReadLines(fileName).Any(line => line.Contains("mySpecialString"));

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