Question

作为C＃.Net编程的新手，我一直在尝试进行一些算术计算，并且当我想要得到零小数的整数时，我一直坚持操作双打，如下面的代码所示

        double a, b;
        a = 2.0;
        b = 2.0;
        double z = a + b;
        Console.WriteLine(z);

输出：4，而不是4.0 请问任何决议？

Answer 1

如果double不是整数（即小数点右边有数字），我假设您不希望舍入输出值，在这种情况下，为所有值格式化为“N1” z的内容是不合适的。

if ((z % 1) == 0)
    Console.WriteLine(z.ToString("N1")); // should output "4.0"
else
    Console.WriteLine(z); // should output "4.123456789"

Answer 2

使用字符串格式执行此操作：

android.support.test.espresso.PerformException: Error performing 'scroll RecyclerView to: holder with view: has descendant: with id: com.refactor:id/header' on view 'with id: com.refactor:id/playing_recycler'. at android.support.test.espresso.PerformException$Builder.build(PerformException.java:83) at android.support.test.espresso.base.DefaultFailureHandler.getUserFriendlyError(DefaultFailureHandler.java:80) at android.support.test.espresso.base.DefaultFailureHandler.handle(DefaultFailureHandler.java:56) at android.support.test.espresso.ViewInteraction.runSynchronouslyOnUiThread(ViewInteraction.java:184) at android.support.test.espresso.ViewInteraction.doPerform(ViewInteraction.java:115) at android.support.test.espresso.ViewInteraction.perform(ViewInteraction.java:87) at com.ui.home.nowplaying.BaseNowPlayingFragmentEspressoTest.checkNowPlayingMoreLikeThisDoesExist(BaseNowPlayingFragmentEspressoTest.java:197) at com.ui.home.playing.LikeThisTest.testThisIsDisplayed(LikeThisTest.java:37) at java.lang.reflect.Method.invoke(Native Method) at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47) at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26) at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27) at android.support.test.internal.statement.UiThreadStatement.evaluate(UiThreadStatement.java:55) at com.test.base.DelayedFinishActivityTestRule$DelayedFinishActivityTestStatement.evaluate(DelayedFinishActivityTestRule.java:226) at android.support.test.rule.ServiceTestRule$ServiceStatement.evaluate(ServiceTestRule.java:329) at org.junit.rules.RunRules.evaluate(RunRules.java:20) at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26) at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27) at org.junit.runners.ParentRunner.run(ParentRunner.java:363) at org.junit.runners.Suite.runChild(Suite.java:128) at org.junit.runners.Suite.runChild(Suite.java:27) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) at org.junit.runners.ParentRunner.run(ParentRunner.java:363) at org.junit.runner.JUnitCore.run(JUnitCore.java:137) at org.junit.runner.JUnitCore.run(JUnitCore.java:115) at android.support.test.internal.runner.TestExecutor.execute(TestExecutor.java:59) at android.support.test.runner.AndroidJUnitRunner.onStart(AndroidJUnitRunner.java:262) at android.app.Instrumentation$InstrumentationThread.run(Instrumentation.java:1996) Caused by: java.lang.RuntimeException: Found more than one sub-view matching holder with view: has descendant: with id: com.refactor:id/header *** Matched ViewHolder item at position: 2 *** View Hierarchy: +>PercentRelativeLayout{id=-1, visibility=VISIBLE, width=0, height=0, has-focus=false, has-focusable=true, has-window-focus=false, is-clickable=false, is-enabled=true, is-focused=false, is-focusable=false, is-layout-requested=true, is-selected=false, root-is-layout-requested=true, has-input-connection=false, x=0.0, y=0.0, child-count=1} | +->TypeFaceTextView{id=2131690060, res-name=more_like_this_header, visibility=VISIBLE, width=0, height=0, has-focus=false, has-focusable=true, has-window-focus=false, is-clickable=false, is-enabled=true, is-focused=false, is-focusable=true, is-layout-requested=true, is-selected=false, root-is-layout-requested=true, has-input-connection=false, x=0.0, y=0.0, text=More like this, input-type=0, ime-target=false, has-links=false} | *** Matched ViewHolder item at position: 7 *** View Hierarchy: +>PercentRelativeLayout{id=-1, visibility=VISIBLE, width=0, height=0, has-focus=false, has-focusable=true, has-window-focus=false, is-clickable=false, is-enabled=true, is-focused=false, is-focusable=false, is-layout-requested=true, is-selected=false, root-is-layout-requested=true, has-input-connection=false, x=0.0, y=0.0, child-count=1} | +->TypeFaceTextView{id=2131690060, res-name=more_like_this_header, visibility=VISIBLE, width=0, height=0, has-focus=false, has-focusable=true, has-window-focus=false, is-clickable=false, is-enabled=true, is-focused=false, is-focusable=true, is-layout-requested=true, is-selected=false, root-is-layout-requested=true, has-input-connection=false, x=0.0, y=0.0, text=More like this, input-type=0, ime-target=false, has-links=false} | at android.support.test.espresso.contrib.RecyclerViewActions$ScrollToViewAction.perform(RecyclerViewActions.java:361) at android.support.test.espresso.ViewInteraction$1.run(ViewInteraction.java:144) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:423) at java.util.concurrent.FutureTask.run(FutureTask.java:237) at android.os.Handler.handleCallback(Handler.java:739) at android.os.Handler.dispatchMessage(Handler.java:95) at android.os.Looper.loop(Looper.java:168) at android.app.ActivityThread.main(ActivityThread.java:5885) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:797) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:687)

N是格式类型（数字），1表示1位小数。

Answer 3

以下是另一种控制小数格式的方法：

        var a = 2.0;
        var b = 2.0;
        double z = a + b;

        Console.WriteLine(string.Format("{0:0.00}", z));
        Console.WriteLine(String.Format("{0:0.0000}", z));

上面的输出：

4.00

4.0000

还有一个例子：

        var a = 2.0;
        var b = 2.2;
        double z = a + b;

        Console.WriteLine(string.Format("{0:0.0}", z));
        Console.WriteLine(String.Format("{0:0.000}", z));

上面的输出：

4.2

4.200

Answer 4

没有问题。数字为4.您写入控制台的字符串是使用隐式格式生成的。要更改此设置，只需定义所需的格式，例如：

Console.WriteLine(@"This is my number {z:N1}");

或

Console.WriteLine(z.ToString("N1");

或

{{1}}

MSDN中的implicit conversion部分解释了字符串的格式化类型如何在.NT中工作。像Formatting Types in the .NET Framework和Console.WriteLine这样的方法允许您指定一个预定义或自定义格式字符串，用于控制值如何转换为字符串

添加双数据类型值

4 个答案: