Question

有人知道我在下面运行代码时出现以下错误的原因吗？

错误：无法指定类型＆＃39; String.CharacterView.index＆＃39;的值输入＆＃39; Int＆＃39;

START TRANSACTION;
select    [col1]    [col3]    from    [table1]    where    [col1]    =    0 ;
UPDATE    [table1]    SET    [col1]    =    1    where    [col1]    =    0;
COMMIT;

更新

我尝试将let lastIndex更改为var lastIndex但没有运气

Answer 1

这是解决问题的简单方法：

let input = "find the longest word in the problem description";

let longest = input
    .characters //get the input characters
    .split(separator:" ", //split by spaces
           maxSplits: 1000, //max number of splits
           omittingEmptySubsequences: true) //omit "" splits
    .map(String.init) //make new strings from the characters
    .max{$0.characters.count < $1.characters.count} //get longest length word

print(longest)

感谢originaluser2

Answer 2

您无法比较lastCheck（Int}和lastIndex（Index）。

你必须转换它：

var problem = "find the longest word in the problem description"
var last = problem.characters.last
let lastIndex = problem.characters.endIndex;
print(last);
var words:[String] = [String]();
var word:String = "";
var lastCheck:Int = 0;
for i in problem.characters{
    lastCheck = lastCheck + 1
    let lastIndexInt = problem.characters.startIndex.distanceTo(end: lastIndex) // new
    if i != " "{
        word = word + String(i)
    }
    else if lastCheck = lastIndex{
        words.append(word);
    }
    else if i == " "{
        words.append(word)
        word = ""
    }
}
print(words)

Answer 3

String.CharacterView.Index是struct，但不是Int。因此，您无法为Int变量分配String.CharacterView.Index。这是正常的。

您必须将@转换为@ Amomchilov的答案，或使用索引：

...
var lastCheck:String.CharacterView.Index = problem.startIndex
for i in problem.characters {
    lastCheck = lastCheck.advancedBy(1)
    ...
}

无论如何，为了找到一个短语的最长单词，你可以使用Swift的builtIn函数来获取所有单词，然后比较它们的长度。例如：

let str = "find the longest word in the problem description"
var longestWord : String?
str.enumerateSubstringsInRange(str.startIndex..<str.endIndex, options:.ByWords) {
    (substring, substringRange, enclosingRange, value) in
    if let _subString = substring {
        if longestWord == nil  || longestWord!.characters.count < _subString.characters.count {
            longestWord = _subString
        }
    }
}

Answer 4

轻松获取句子中的所有单词

var problem = "find the longest word in the problem description"
problem.enumerateSubstrings(in: (problem.range(of: problem))!, options: NSString.EnumerationOptions.byWords, { (substring, substringRange, enclosingRange, stop) -> () in

print(substring)
})

轻松获得句子中最长的单词

var longestWord = ""
problem.enumerateSubstrings(in: (problem.range(of: problem))!, options: NSString.EnumerationOptions.byWords, { (substring, substringRange, enclosingRange, stop) -> () in
if longestWord.characters.count < substring?.characters.count{
    longestWord = substring!
}
})
print(longestWord)

注意：代码参考Swift 3.对于较低版本会有一些语法更改。让我知道你是否需要相同的较低版本。

Swift：无法赋值类型＆＃39; String.CharacterView.index＆＃39;输入＆＃39; Int＆＃39;

4 个答案: