在c#中计算大写字符数的最快方法
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/609704/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Fastest way to count number of uppercase characters in c#
提问by peterorum
Any thoughts on the efficiency of this? ...
关于这个效率的任何想法？...
CommentText.ToCharArray().Where(c => c >= 'A' && c <= 'Z').Count()
采纳答案by Matt Hamilton
Ok, just knocked up some code to time your method against this:
好的，只是敲了一些代码来为你的方法计时：
int count = 0;
for (int i = 0; i < s.Length; i++)
{
if (char.IsUpper(s[i])) count++;
}
The result:
结果：
Yours: 19737 ticks
Mine: 118 ticks
您的：19737 个滴答声
我的：118 滴答
Pretty big difference! Sometimes the most straight-forward way is the most efficient.
相当大的不同！有时，最直接的方法是最有效的。
Edit
编辑
Just out of interest, this:
只是出于兴趣，这个：
int count = s.Count(c => char.IsUpper(c));
Comes in at at around 2500 ticks. So for a "Linqy" one-liner it's pretty quick.
在大约 2500 个滴答声中出现。所以对于“Linqy”单线来说，它非常快。
回答by Dead account
You're only counting standard ASCII and not ?Dê etc.
你只计算标准 ASCII 而不是 ?Dê 等。
How about
怎么样
CommentText.ToCharArray().Where(c => Char.IsUpper(c)).Count()
回答by Binary Worrier
Without even testing I'd say
我什至没有测试我会说
int count = 0;
foreach (char c in commentText)
{
if (Char.IsUpper(c))
count++;
}
is faster, off now to test it.
更快，现在关闭来测试它。
回答by chuckj
First there is no reason you need to call ToCharArray()since, assuming CommentTextis a string it is already an IEnumerable<char>. Second, you should probably be calling char.IsUpperinstead of assuming you are only dealing with ASCII values. The code should really look like,
首先，您没有理由需要调用，ToCharArray()因为假设CommentText是一个字符串，它已经是一个IEnumerable<char>. 其次，您可能应该调用char.IsUpper而不是假设您只处理 ASCII 值。代码应该看起来像，
CommentText.Count(char.IsUpper)
Third, if you are worried about speed there isn't much that can beat the old for loop,
第三，如果你担心速度，没有什么可以打败旧的 for 循环，
int count = 0;
for (int i = 0; i < CommentText.Length; i++)
if (char.IsUpper(CommentText[i]) count++;
In general, calling any method is going to be slower than inlining the code but this kind of optimization should only be done if you are absolutely sure this is the bottle-neck in your code.
一般来说，调用任何方法都会比内联代码慢，但只有在您绝对确定这是代码中的瓶颈时才应该进行这种优化。
回答by Guffa
What you are doing with that code is to create a collection with the characters, then create a new collection containing only the uppercase characters, then loop through that collection only to find out how many there are.
您使用该代码所做的是创建一个包含字符的集合，然后创建一个仅包含大写字符的新集合，然后遍历该集合以找出有多少个字符。
This will perform better (but still not quite as good as a plain loop), as it doesn't create the intermediate collections:
这会表现得更好（但仍然不如普通循环好），因为它不会创建中间集合：
CommentText.Count(c => Char.IsUpper(c))
Edit: Removed the ToCharArray call also, as Matt suggested.
编辑：也删除了 ToCharArray 调用，正如马特建议的那样。
回答by flq
I've got this
我有这个
Regex x = new Regex("[A-Z]{1}",
RegexOptions.Compiled | RegexOptions.CultureInvariant);
int c = x.Matches(s).Count;
but I don't know if its particularly quick. It won't get special chars either, I s'pose
但我不知道它是否特别快。它也不会得到特殊字符，我想
EDIT:
编辑：
Quick comparison to this question's answer. Debug in vshost, 10'000 iterations with the string:
aBcDeFGHi1287jKK6437628asghwHllmTbynerA
快速比较这个问题的答案。在 vshost 中调试，使用字符串进行 10'000 次迭代：
aBcDeFGHi1287jKK6437628asghwHllmTbynerA
- The answer: 20-30 ms
- The regex solution: 140-170 ms
- 答案：20-30 毫秒
- 正则表达式解决方案：140-170 毫秒
