收到“UnsafeMutableRawPointer”类型的错误消息没有下标成员

Posted 2023-03-14

【中文标题】收到“UnsafeMutableRawPointer”类型的错误消息没有下标成员

【英文标题】：getting error message of Type 'UnsafeMutableRawPointer' has no subscript members'

【发布时间】：2018-10-10 05:42:45

【问题描述】：

我只需要在那里分配内存和设置值。这是我的代码。

 let radius:Float = 5.79
 let sigma:Float = radius / 2
 let size:Int = Int((round(radius) * 2) + 1)

 var weights:UnsafeMutableRawPointer = malloc(MemoryLayout<Float>.size * size * size)

 weights[some index] = some vale

但我在 swift 版本 4 中收到一条错误消息，提示“UnsafeMutableRawPointer 没有下标成员”

我该如何解决这个问题。请有任何想法

【参考方案1】：

你最好查看UnsafeMutableRawPointer的官方文档

你可以这样写：

let radius:Float = 5.79
let sigma:Float = radius / 2
let size:Int = Int((round(radius) * 2) + 1)

var weights:UnsafeMutableRawPointer = malloc(MemoryLayout<Float>.size * size * size)

weights.storeBytes(of: some value, toByteOffset: some offset, as: SomeType.self)

如果所有元素都是Float，则最好使用UnsafeMutablePointer<Float>。

var weights:UnsafeMutablePointer<Float> = UnsafeMutablePointer.allocate(capacity: size * size)

weights[some index] = some vale