C#：在txt文件中搜索一行，程序返回其中写入的值

Question

txt文件最多有300行，每行只有一个数字，数字在0到30之间。

Answer 1

只需将此函数放入您的程序中并调用它即可：

find_string("text for search","list file path");

返回值是包含该函数的行，如果未找到匹配项，则返回空字符串。

public static string find_string(string search,string path) 
// This method opens your list file and searches for the string 
// that you passed as arg1 then return first match.
        {
            using (StreamReader sr = new StreamReader(File.OpenRead(path)))
            {
                while (!sr.EndOfStream)
                {
                    string line = sr.ReadLine();
                    if (line != null && line.Contains(search))
                    {
                        return line;
                    }
                }
                return "";
            }//close stream after reach to end of using block
        }