Question

当我写Console.WriteLine( new Point (1,1));时，它不会调用方法ToString。但它将对象转换为Int32，并将其写入控制台。但为什么？它似乎忽略了被覆盖的方法ToString。

struct Point
{
    public Int32 x;
    public Int32 y;

    public Point(Int32 x1,Int32 y1)
    {
        x = x1;
        y = y1;
    }

    public static Point operator +(Point p1, Point p2)
    {
        return new Point(p1.x + p2.x, p1.y + p2.y); 
    }


    public static implicit operator Int32(Point p)
    {
        Console.WriteLine("Converted to Int32");
        return p.y + p.x;
    }

    public override string ToString()
    {
        return String.Format("x = {0}  |  y = {1}", x, y);
    }
}

Answer 1

原因是隐式转换为Int32 （您可能知道）。

Console.WriteLine有许多重载需要String，Object和其他人，包括Int32。

由于Point可隐式转换为Int32，因此使用int的{{1}} overload，这也会进行隐式转换。

这可以通过以下方式解决：

Console.WriteLine

您可以在Overload Resolution in C#中找到有关它的更多信息。

否则，最好的函数成员是一个函数成员比给定的所有其他功能成员更好参数列表，只要将每个函数成员与所有函数成员进行比较其他功能成员使用Section 7.4.2.2 中的规则。

还有：

7.4.2.2 Better function member

对于每个参数，从AX到PX的隐式转换不是比从AX到QX的隐式转换更糟糕，

Answer 2

这是因为结构类型中的隐式转换，即以下行：

16/01/22 15:51:50 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
16/01/22 15:51:51 INFO client.RMProxy: Connecting to ResourceManager at /0.0.0.0:8032
16/01/22 15:51:51 INFO input.FileInputFormat: Total input paths to process : 33
16/01/22 15:51:52 INFO mapreduce.JobSubmitter: number of splits:33
16/01/22 15:51:52 INFO mapreduce.JobSubmitter: Submitting tokens for job: job_1453492366595_0009
16/01/22 15:51:52 INFO impl.YarnClientImpl: Submitted application application_1453492366595_0009
16/01/22 15:51:52 INFO mapreduce.Job: The url to track the job: http://Marys-MacBook-Pro.local:8088/proxy/application_1453492366595_0009/
16/01/22 15:51:52 INFO mapreduce.Job: Running job: job_1453492366595_0009
16/01/22 15:51:56 INFO mapreduce.Job: Job job_1453492366595_0009 running in uber mode : false
16/01/22 15:51:56 INFO mapreduce.Job:  map 0% reduce 0%
16/01/22 15:51:56 INFO mapreduce.Job: Job job_1453492366595_0009 failed with state FAILED due to: Application application_1453492366595_0009 failed 2 times due to AM Container for appattempt_1453492366595_0009_000002 exited with  exitCode: 127
For more detailed output, check application tracking page:http://Marys-MacBook-Pro.local:8088/cluster/app/application_1453492366595_0009Then, click on links to logs of each attempt.
Diagnostics: Exception from container-launch.
Container id: container_1453492366595_0009_02_000001
Exit code: 127
Stack trace: ExitCodeException exitCode=127: 
    at org.apache.hadoop.util.Shell.runCommand(Shell.java:545)
    at org.apache.hadoop.util.Shell.run(Shell.java:456)
    at org.apache.hadoop.util.Shell$ShellCommandExecutor.execute(Shell.java:722)
    at org.apache.hadoop.yarn.server.nodemanager.DefaultContainerExecutor.launchContainer(DefaultContainerExecutor.java:211)
    at org.apache.hadoop.yarn.server.nodemanager.containermanager.launcher.ContainerLaunch.call(ContainerLaunch.java:302)
    at org.apache.hadoop.yarn.server.nodemanager.containermanager.launcher.ContainerLaunch.call(ContainerLaunch.java:82)
    at java.util.concurrent.FutureTask.run(FutureTask.java:262)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:745)


Container exited with a non-zero exit code 127
Failing this attempt. Failing the application.

因此编译器通过调用上面的隐式转换方法将Point类型视为整数。

要解决此问题，您需要从您的类型中删除隐式转换，或者在执行Console.WriteLine（）时放置ToString（）方法

这应该可以解决您的问题。希望这会有所帮助。

最佳

使用转换方法覆盖类型中的虚方法

2 个答案: