Csharp 在文本文件中搜索字符串，如果未找到字符串则执行某个操作

使用以下方法查找出现搜索文本的行号.如果在文件中未找到搜索文本，则该方法返回一个空列表.

/// <summary>
/// Searches the specified file for a given word.
/// </summary>
/// <param name="filePath">Full path of the file.</param>
/// <param name="word">Search text.</param>
/// <returns>The line numbers of the occurences.</returns>
public List<int> SearchWord(string filePath, string word)
{
    var occurences = new List<int>();
    var lines = File.ReadAllLines(filePath);
    for (int i = 0; i < lines.Length; i++)
    {
        string currentLine = lines[i];
        if (currentLine.Contains(word))
        {
            occurences.Add(i + 1);
        }
    }
    return occurences;
}

要从Button次单击处理程序使用该方法，请执行以下操作:

private void BtnSearchFile_Click(object sender, EventArgs e)
{
    string filePath = @"D:\Test.txt";
    string word = TxtSearchTerm.Text;
    List<int> occurences = SearchWord(filePath, word);
    if (occurences.Any())
    {
        string lines = string.Join(",", occurences);
        string message = $"The word '{word}' occurs in lines {lines}";
        MessageBox.Show(message);
    }
    else
    {
        string message = $"The word '{word}' could not be found in the file.";
        MessageBox.Show(message);
    }
}

结果(找到时):