如何读取文件或流，直到找到字符串

with open('file.txt', 'r') as file:
    for line in file:
        if 'target_string' in line:
            # 处理找到的字符串
            print(line)
            break

try (BufferedReader reader = new BufferedReader(new FileReader("file.txt"))) {
    String line;
    while ((line = reader.readLine()) != null) {
        if (line.contains("target_string")) {
            // 处理找到的字符串
            System.out.println(line);
            break;
        }
    }
} catch (IOException e) {
    e.printStackTrace();
}

using (StreamReader reader = new StreamReader("file.txt")) {
    string line;
    while ((line = reader.ReadLine()) != null) {
        if (line.Contains("target_string")) {
            // 处理找到的字符串
            Console.WriteLine(line);
            break;
        }
    }
}