blocks|key|1863540|text|试试这个：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1863541|func+asciiCStringToSwiftString(cString:UnsafePointer<UInt8>,+maxLength:Int)+->+String
{
++++var+swiftString+=+String()++//+The+Swift+String+to+be+Returned+is+Intialized+to+an+Empty+String
++++var+workingCharacter:UnicodeScalar+=+UnicodeScalar(cString[0])
++++var+count:Int+=+0+++++++++++//+An+Index+Into+the+C+String+Array+Starting+With+the+First+Character

++++while+cString[count]+!=+0+++++++++++++//+While+We+Haven't+reached+the+End+of+the+String
++++{
++++++++workingCharacter+=+UnicodeScalar(cString[count])+//+Convert+the+ASCII+Character+to+a+Unicode+Scalar
++++++++swiftString.append(workingCharacter)+++++++++++++//+Append+the+Unicode+Scalar+Version+of+the+ASCII+Character
++++++++count%2B%2B++++++++++++++++++++++++++++++++++++++++++//+Increment+the+Index+to+Look+at+the+Next+ASCII+Character

++++++++if+count+>+maxLength++++++++++++++++++++++++++++//+Set+a+Limit+In+Case+the+C+string+was+Not+NULL+Terminated
++++++++{
++++++++++++if+printDebugLogs+==+true
++++++++++++{
++++++++++++++++swiftString="Reached+String+Length+Limit+in+Converting+ASCII+C+String+To+Swift+String"
++++++++++++}
++++++++++++return+swiftString
++++++++}
++++}

++++return+swiftString+++++++++++++++++++++//+Return+the+Swift+String
}|code-block|syntax|javascript|1863542|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Try this:

<pre><code>func asciiCStringToSwiftString(cString:UnsafePointer&lt;UInt8&gt;, maxLength:Int) -&gt; String
{
 var swiftString = String() // The Swift String to be Returned is Intialized to an Empty String
 var workingCharacter:UnicodeScalar = UnicodeScalar(cString[0])
 var count:Int = 0 // An Index Into the C String Array Starting With the First Character

 while cString[count] != 0 // While We Haven't reached the End of the String
 {
 workingCharacter = UnicodeScalar(cString[count]) // Convert the ASCII Character to a Unicode Scalar
 swiftString.append(workingCharacter) // Append the Unicode Scalar Version of the ASCII Character
 count++ // Increment the Index to Look at the Next ASCII Character

 if count &gt; maxLength // Set a Limit In Case the C string was Not NULL Terminated
 {
 if printDebugLogs == true
 {
 swiftString="Reached String Length Limit in Converting ASCII C String To Swift String"
 }
 return swiftString
 }
 }

 return swiftString // Return the Swift String
}
</code></pre>

blocks|key|2077089|text|实际上，您可以使用Swift的可变参数语法将元组收集到数组中：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2077090|let+record+=+getRecord()
let+(int8s:+Int8...)+=+myRecord++++++++++//+int8s+is+an+[Int8]
let+uint8s+=+int8s.map+{+UInt8($0)+}
let+string+=+String(bytes:+uint8s,+encoding:+NSASCIIStringEncoding)
//+myString+==+Optional("12345678")|code-block|syntax|javascript|2077091|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You can actually collect a tuple into an array by using Swift's variadic parameter syntax:

<pre><code>let record = getRecord()
let (int8s: Int8...) = myRecord // int8s is an [Int8]
let uint8s = int8s.map { UInt8($0) }
let string = String(bytes: uint8s, encoding: NSASCIIStringEncoding)
// myString == Optional("12345678")
</code></pre>

blocks|key|1863621|text|我对自己的目的也很感兴趣，所以我添加了一个新函数：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1863622|func+asciiCArrayToSwiftString(cString:Int8...)+->+String
{
++++var+swiftString+=+String()++++++++++++//+The+Swift+String+to+be+Returned+is+Intialized+to+an+Empty+String
++++var+workingCharacter:UnicodeScalar+=+UnicodeScalar(UInt8(cString[0]))
++++var+count:Int+=+cString.count

++++for+var+i:Int+=+0;+i+<+count;+i%2B%2B
++++{
++++++++workingCharacter+=+UnicodeScalar(UInt8(cString[i]))+//+Convert+the+Int8+Character+to+a+Unicode+Scalar
++++++++swiftString.append(workingCharacter)+++++++++++++//+Append+the+Unicode+Scalar

++++}

++++return+swiftString+++++++++++++++++++++//+Return+the+Swift+String
}|code-block|syntax|javascript|1863623|我使用以下命令调用此函数：|1863624|++++let+t:Int8+=+Int8(116)
++++let+e:Int8+=+Int8(101)
++++let+s:Int8+=+Int8(115)
++++let+testCString+=+(t,+e,+s,+t)
++++let+testSwiftString+=+wispStringConverter.asciiCArrayToSwiftString(testCString.0,+testCString.1,+testCString.2,+testCString.3)
++++println("testSwiftString+=+\(testSwiftString)")|1863625|结果输出为：|1863626|testSwiftString+=测试|1863627|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|V|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

I'm interested in working this out for my own purposes as well, so I added a new function:

<pre><code>func asciiCArrayToSwiftString(cString:Int8...) -&gt; String
{
 var swiftString = String() // The Swift String to be Returned is Intialized to an Empty String
 var workingCharacter:UnicodeScalar = UnicodeScalar(UInt8(cString[0]))
 var count:Int = cString.count

 for var i:Int = 0; i &lt; count; i++
 {
 workingCharacter = UnicodeScalar(UInt8(cString[i])) // Convert the Int8 Character to a Unicode Scalar
 swiftString.append(workingCharacter) // Append the Unicode Scalar

 }

 return swiftString // Return the Swift String
}
</code></pre>

I call this function with:

<pre><code> let t:Int8 = Int8(116)
 let e:Int8 = Int8(101)
 let s:Int8 = Int8(115)
 let testCString = (t, e, s, t)
 let testSwiftString = wispStringConverter.asciiCArrayToSwiftString(testCString.0, testCString.1, testCString.2, testCString.3)
 println("testSwiftString = \(testSwiftString)")
</code></pre>

the resulting output is:

testSwiftString = test

blocks|key|1863662|text|下面是我想出的一个解决方案，它使用反射将元组实际转换为Int8，然后使用fromCString...()方法将其转换为字符串。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1863663|func+arrayForTuple<T,E>(tuple:T)+->+[E]+{
++++let+reflection+=+reflect(tuple)
++++var+arr+:+[E]+=+[]
++++for+i+in+0..<reflection.count+{
++++++++if+let+value+=+reflection[i].1.value+as?+E+{
++++++++++++arr.append(value)
++++++++}
++++}
++++return+arr
}

public+extension+String+{
++++public+static+func+fromTuple<T>(tuple:T)+->+String?+{
++++++++var+charArray+=+arrayForTuple(tuple)+as+[Int8]
++++++++var+nameString+=+String.fromCString(UnsafePointer<CChar>(charArray))
++++++++if+nameString+==+nil+{
++++++++++++nameString+=+String.fromCStringRepairingIllFormedUTF8(UnsafePointer<CChar>(charArray)).0
++++++++}
++++++++return+nameString
++++}
}|code-block|syntax|javascript|1863664|entityMap|0|LINK|mutability|MUTABLE|url|see+[Any+way+to+iterate+a+tuple+in+swift?](https://stackoverflow.com/questions/24299045/any-way-to-iterate-a-tuple-in-swift)^0|R|4|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

Here's a solution I came up with which uses reflection to actually convert the tuple into an [Int8] (see <a href="https://stackoverflow.com/questions/24299045/any-way-to-iterate-a-tuple-in-swift">Any way to iterate a tuple in swift?</a>), and then converts it to a string using fromCString...() methods.

<pre><code>func arrayForTuple&lt;T,E&gt;(tuple:T) -&gt; [E] {
 let reflection = reflect(tuple)
 var arr : [E] = []
 for i in 0..&lt;reflection.count {
 if let value = reflection[i].1.value as? E {
 arr.append(value)
 }
 }
 return arr
}

public extension String {
 public static func fromTuple&lt;T&gt;(tuple:T) -&gt; String? {
 var charArray = arrayForTuple(tuple) as [Int8]
 var nameString = String.fromCString(UnsafePointer&lt;CChar&gt;(charArray))
 if nameString == nil {
 nameString = String.fromCStringRepairingIllFormedUTF8(UnsafePointer&lt;CChar&gt;(charArray)).0
 }
 return nameString
 }
}
</code></pre>

blocks|key|1863670|text|Swift+3.仅使用反射。此版本在遇到空字节时停止构建字符串。测试过了。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1863671|func+TupleOfInt8sToString(+_+tupleOfInt8s:Any+)+->+String?+{
++++var+result:String?+=+nil
++++let+mirror+=+Mirror(reflecting:+tupleOfInt8s)

++++for+child+in+mirror.children+{
++++++++guard+let+characterValue+=+child.value+as?+Int8,+characterValue+!=+0+else+{
++++++++++++break
++++++++}

++++++++if+result+==+nil+{
++++++++++++result+=+String()
++++++++}
++++++++result?.append(Character(UnicodeScalar(UInt8(characterValue))))
++++}

++++return+result
}|code-block|syntax|javascript|1863672|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Swift 3. Only uses reflection. This version stops building the string when it encounters a null byte. Tested.

<pre><code>func TupleOfInt8sToString( _ tupleOfInt8s:Any ) -&gt; String? {
 var result:String? = nil
 let mirror = Mirror(reflecting: tupleOfInt8s)

 for child in mirror.children {
 guard let characterValue = child.value as? Int8, characterValue != 0 else {
 break
 }

 if result == nil {
 result = String()
 }
 result?.append(Character(UnicodeScalar(UInt8(characterValue))))
 }

 return result
}
</code></pre>

blocks|key|1863689|text|我刚刚在使用Swift+3.+(3.0.2)时遇到了类似的问题。我试图在Swift中将CChar，CChar的数组转换为字符串。原来Swift+3有一个字符串初始化器，它将接受一个cString。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1863690|示例：|1863691|let+a+=+"abc".cString(using:+.utf8)+//+type+of+a+is+[CChar]
let+b+=+String(cString:+a!,+encoding:+.utf8)+//+type+of+b+is+String
print("a+=+\(a)")
print("b+=+\(b)")|code-block|syntax|javascript|1863692|结果：|1863693|A=可选(97、98、99、0)|1863694|B=可选(“abc”)|1863695|请注意，字符串上的cString函数会产生一个可选的。当在创建b的String.init函数中使用它时，它必须被强制解包。这意味着两者最终都可能为零，因此也应该使用错误检查。|1863696|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|V|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|W|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|X|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|Y|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

I have just experienced a similar issue using Swift 3. (3.0.2). I was attempting to convert an Array of CChar, [CChar] to a String in Swift. It turns out Swift 3 has a String initializer which will take a cString.

Example:

<pre><code>let a = "abc".cString(using: .utf8) // type of a is [CChar]
let b = String(cString: a!, encoding: .utf8) // type of b is String
print("a = \(a)")
print("b = \(b)")
</code></pre>

results in

a = Optional([97, 98, 99, 0])

b = Optional("abc")

Note that the cString function on String results in an Optional. It must be force unwrapped when used in the String.init function creating b. And b is also Optional... meaning both could end up being nil, so error checking should also be used.

I have a Swift program that does interop with a C library. This C library returns a structure with a <code>char[]</code> array inside, like this:

<pre><code>struct record
{
 char name[8];
};
</code></pre>

The definition is correctly imported into Swift. However, the field is interpreted as a tuple of 8 <code>Int8</code> elements (typed <code>(Int8, Int8, Int8, Int8, Int8, Int8, Int8, Int8)</code>), which I have no idea how to transform into a <code>String</code> with Swift.

There is no <code>String</code> initializer that accepts an <code>Int8</code> tuple, and it doesn't seem possible to get a pointer to the first element of the tuple (since types can be heterogenous, that's not really surprising).

Right now, my best idea is to create a tiny C function that accepts a pointer to the structure itself and return <code>name</code> as a <code>char*</code> pointer instead of an array, and go with that.

Is there, however, are pure Swift way to do it?

Converting a C char array to a String

我有一个与C库进行互操作的Swift程序。这个C库返回一个内部有char[]数组的结构，如下所示：struct record{    char name[8];};定义已正确导入Swift。但是，该字段被解释为8个Int8元素(类型为(Int8, Int8, Int8, Int8, Int8, Int8, Int8, ...

问将C字符数组转换为字符串
EN

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问将C字符数组转换为字符串EN

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问将C字符数组转换为字符串
EN