英文:
Are there uint64 literals in Go?
问题
我正在查看Go语言中的数字类型。我想要使用uint64字面量，这在Go语言中是否可行？
以下是我想要使用uint64字面量的示例代码：
for i := uint64(2); i <= k; i += 1 { // 我希望i是一个uint64类型
...
}
英文:
I'm looking at the numeric types in Go. I want to use uint64 literals. Is this possible in Go?
Here's an example of how I'd like to use uint64 literals:
for i := 2; i <= k; i += 1 { // I want i to be a uint64
...
}
答案1
得分: 18
你可以将整数字面量直接转换为uint64类型。
for i := uint64(1); i <= k; i++ {
// 做一些操作
}
或者你可以在for循环外部初始化i，但这样它的作用域就比循环本身要大。
var i uint64
for i = 1; i <= k; i++ {
// 注意使用`=`而不是`:=`
}
// i仍然存在，并且现在的值是k+1
英文:
you can just cast your integer literal to uint64.
for i := uint64(1); i <= k; i++ {
// do something
}
Alternatively you could initialize i outside of the for loop, but then it's scoped larger than the loop itself.
var i uint64
for i = 1; i <= k; i++ {
// note the `=` instead of the `:=`
}
// i still exists and is now k+1
答案2
得分: 3
让我们来看一下常量的规范：https://go.dev/ref/spec#Constants。他们说：
常量可以通过常量声明或转换显式地给定类型，或者在变量声明、赋值或表达式的操作数中隐式地给定类型。
并且：
无类型常量具有默认类型，该类型是在需要类型化值的上下文中隐式转换为常量的类型，例如，在没有显式类型的短变量声明中，如
i := 0。无类型常量的默认类型分别为bool、rune、int、float64、complex128或string，具体取决于它是布尔、符文、整数、浮点、复数还是字符串常量。
根据这些说明，并结合你的代码上下文，初始化一个不在默认类型列表中的变量（如uint64）的最佳方法是进行转换：
for i := uint64(2); i <= k; i++ {
...
}
英文:
Let's take a look at the specification for constant: https://go.dev/ref/spec#Constants. This is what they said:
> A constant may be given a type explicitly by a constant declaration or conversion, or implicitly when used in a variable declaration or an assignment or as an operand in an expression.
And:
> An untyped constant has a default type which is the type to which the constant is implicitly converted in contexts where a typed value is required, for instance, in a short variable declaration such as i := 0 where there is no explicit type. The default type of an untyped constant is bool, rune, int, float64, complex128 or string respectively, depending on whether it is a boolean, rune, integer, floating-point, complex, or string constant.
Based on these statements and in the context of your code, the best way to initialize a variable that is not in the default type list like uint64 it to convert:
for i := uint64(2); i <= k; i++ {
...
}
答案3
得分: 0
你必须明确声明变量的类型。int字面量将是int类型，例如var i uint64。在你的示例中，你还需要更改赋值部分，像这样：
var i uint64
for i = 2; i <= k; i += 1 { // 我希望i是uint64类型
...
}
英文:
You have to explicitly declare your variables as that type. The int literal will be of type int https://play.golang.org/p/OgaZzmpLfB something like var i uint64 is required. In your example you'd have to change your assignment as well so something like this;
var i uint64
for i = 2; i <= k; i += 1 { // I want i to be a uint64
...
}
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