为什么＆QUOT;餐饮QUOT;花车声明时，需要？ [英] Why is the "f" required when declaring floats?

问题描述

例如：

float timeRemaining = 0.58f;

为什么˚F是在数端所需？

推荐答案

您一个浮动的声明包含两个部分：

Your declaration of a float contains two parts:

1. 这声明变量 timeRemaining 的类型为浮动。


2. 它将值 0.58 这个变量。

1. It declares that the variable timeRemaining is of type float.
2. It assigns the value 0.58 to this variable.

在第2部分出现问题。

右手侧自行评估。根据C＃规范，内容不具有后缀小数点的数字是PTED为跨$ P $一个双击。

The right-hand side is evaluated on its own. According to the C# specification, a number containing a decimal point that doesn't have a suffix is interpreted as a double.

所以，我们现在有一个，我们想分配给键入浮动的变量双值。为了做到这一点，必须有从的隐式转换的双到浮动。有没有这样的转换，因为你可能（在这种情况下做）在转换丢失信息。

So we now have a double value that we want to assign to a variable of type float. In order to do this, there must be an implicit conversion from double to float. There is no such conversion, because you may (and in this case do) lose information in the conversion.

其原因是由编译器使用的值是不是真的0.58，但最接近0.58浮点值，这是0.57999999999999978655962351581366 ...为双击 ，准确0.579999946057796478271484375为浮动。

The reason is that the value used by the compiler isn't really 0.58, but the floating-point value closest to 0.58, which is 0.57999999999999978655962351581366... for double and exactly 0.579999946057796478271484375 for float.

严格说来，˚F不是必需的。您可避免由值转换为一浮动使用˚F说明：

Strictly speaking, the f is not required. You can avoid having to use the f suffix by casting the value to a float:

float timeRemaining = (float)0.58;

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