英文:
Cast/convert int to rune in Go
问题
假设我有一个表示有效Unicode码点的int64变量（或其他整数大小），我想将其转换为Go中的rune，我该怎么做？
在C中，我会使用类型转换，类似于：
c = (char) i; // 仅限7位ASCII
但在Go中，类型断言不起作用：
c, err = rune.( i)
有什么建议吗？
英文:
Assuming I have an int64 variable (or other integer size) representing a valid unicode code-point, and I want to convert it into a rune in Go, what do I do?
In C I would have used a type cast something like:
c = (char) i; // 7 bit ascii only
But in Go, a type assertion won't work:
c, err = rune.( i)
Suggestions?
答案1
得分: 21
你只需要 rune(i)。类型转换通过 type(x) 来完成。
类型断言是另一回事。当你需要从一个不太具体的类型（比如 interface{}）转换为一个更具体的类型时，你会使用类型断言。此外，类型转换在编译时进行检查，而类型断言在运行时发生。
以下是如何使用类型断言的示例：
var (
x interface{}
y int
z string
)
x = 3
// x 现在本质上是被封装的。它的类型是 interface{}，但它包含一个 int。
// 这在某种程度上类似于其他语言中的 Object 类型
// （尽管不完全相同）。
y = x.(int) // 成功
z = x.(string) // 编译通过，但在运行时失败
英文:
You just want rune(i). Casting is done via type(x).
Type assertions are something different. You use a type assertion when you need to go from a less specific type (like interface{}) to a more specific one. Additionally, a cast is checked at compile time, where type assertions happen at runtime.
Here's how you use a type assertion:
var (
x interface{}
y int
z string
)
x = 3
// x is now essentially boxed. Its type is interface{}, but it contains an int.
// This is somewhat analogous to the Object type in other languages
// (though not exactly).
y = x.(int) // succeeds
z = x.(string) // compiles, but fails at runtime
答案2
得分: 3
在Go语言中，你想要进行一次转换。
转换是形式为
T(x)的表达式，其中T是一个类型，x是一个可以转换为类型T的表达式。转换 = 类型 "(" 表达式 ")" .一个非常量值
x可以在以下任何情况下转换为类型T：
x可以赋值给T。x的类型和T具有相同的基础类型。x的类型和T是未命名指针类型，并且它们的指针基础类型具有相同的基础类型。x的类型和T都是整数或浮点数类型。x的类型和T都是复数类型。x是一个整数或具有类型[]byte或[]rune，而T是一个字符串类型。x是一个字符串，而T是[]byte或[]rune。
你想要将类型为int、int32或int64的x转换为类型为rune的T，其中rune是int32类型的别名。x的类型和T都是整数类型。
因此，T(x)是允许的，并且可以写为rune(x)，对于你的例子，c = rune(i)。
英文:
In Go, you want to do a conversion.
> Conversions
>
> Conversions are expressions of the form T(x) where T is a type and
> x is an expression that can be converted to type T.
>
> Conversion = Type "(" Expression ")" .
>
> A non-constant value x can be converted to type T in any of these
> cases:
>
> * x is assignable to T.
> * x's type and T have identical underlying types.
> * x's type and T are unnamed pointer types and their pointer base types have identical underlying types.
> * x's type and T are both integer or floating point types.
> * x's type and T are both complex types.
> * x is an integer or has type []byte or []rune and T is a string type.
> * x is a string and T is []byte or []rune.
You want to convert x, of type int, int32, or int64, to T of type rune, an alias for type int32. x's type and T are both integer types.
Therefore, T(x) is allowed and is written rune(x), for your example, c = rune(i).
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