blocks|key|1113087|text|假设您所说的“英语字符”仅仅指的是26个字符的拉丁字母表，我将在这里使用正则表达式：%5E[a-zA-Z0-9+]*$|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1113088|例如：|1113089|if(+Regex.IsMatch(Console.ReadLine(),+"%5E[a-zA-Z0-9]*$")+)
{+/*+your+code+*/+}|code-block|syntax|javascript|1113090|在这种情况下，正则表达式的好处是，您真正关心的是字符串是否与模式匹配-这是正则表达式非常有效的一个方面。它清楚地捕捉到了你的意图，如果你对“英文字符”的定义超出了26个字母的范围，那么它很容易扩展。|1113091|有一个不错的series+of+articles+here，它教授了更多关于正则表达式的知识。|1113092|Jørn+Schou-Rode的回答很好地解释了这里给出的正则表达式是如何匹配您的输入的。|1113093|entityMap|0|LINK|mutability|MUTABLE|url|http://www.radsoftware.com.au/articles/regexlearnsyntax.aspx^0|16|F|0|0|0|0|6|N|0|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@$9|11|A|12|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|13|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|14|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|15|8|@]|D|@]|E|$]]|$1|O|3|P|5|6|7|16|8|@]|D|@$9|17|A|18|1|19]]|E|$]]|$1|Q|3|R|5|6|7|1A|8|@]|D|@]|E|$]]|$1|S|3|-4|5|6|7|1B|8|@]|D|@]|E|$]]]|T|$U|$5|V|W|X|E|$Y|Z]]]]

Assuming that by "English characters" you are simply referring to the 26-character Latin alphabet, this would be an area where I would use regular expressions: <code>^[a-zA-Z0-9 ]*$</code>

For example:

<pre><code>if( Regex.IsMatch(Console.ReadLine(), "^[a-zA-Z0-9]*$") )
{ /* your code */ }
</code></pre>

The benefit of regular expressions in this case is that all you really care about is whether or not a string matches a pattern - this is one where regular expressions work wonderfully. It clearly captures your intent, and it's easy to extend if you definition of "English characters" expands beyond just the 26 alphabetic ones.

There's a decent <a href="http://www.radsoftware.com.au/articles/regexlearnsyntax.aspx" rel="noreferrer">series of articles here</a> that teach more about regular expressions.

Jørn Schou-Rode's answer provides a great explanation of how the regular expression presented here works to match your input.

blocks|key|1328563|text|另一种方法是检查IsLower和IsUpper是否都没有返回true。类似于：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1328564|++++private+bool+IsAllCharEnglish(string+Input)
++++{
++++++++foreach+(var+item+in+Input.ToCharArray())
++++++++{
++++++++++++if+(!char.IsLower(item)+&&+!char.IsUpper(item)+&&+!char.IsDigit(item)+&&+!char.IsWhiteSpace(item))
++++++++++++{
++++++++++++++++return+false;
++++++++++++}
++++++++}
++++++++return+true;
++++}|code-block|syntax|javascript|1328565|为了使用它：|1328566|++++++++string+str+=+"فارسی+abc";
++++++++IsAllCharEnglish(str);+//+return+false
++++++++str+=+"These+are+english+123";
++++++++IsAllCharEnglish(str);+//+return+true|1328567|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

One other way is to check if IsLower and IsUpper both doesn't return true. 
Something like :

<pre><code> private bool IsAllCharEnglish(string Input)
 {
 foreach (var item in Input.ToCharArray())
 {
 if (!char.IsLower(item) &amp;&amp; !char.IsUpper(item) &amp;&amp; !char.IsDigit(item) &amp;&amp; !char.IsWhiteSpace(item))
 {
 return false;
 }
 }
 return true;
 }
</code></pre>

and for use it :

<pre><code> string str = "فارسی abc";
 IsAllCharEnglish(str); // return false
 str = "These are english 123";
 IsAllCharEnglish(str); // return true
</code></pre>

blocks|key|1328325|text|您是否可以访问web？我假设这是不能保证的，但是Google有一个语言api可以检测你传递给它的语言。google+language+api|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1328326|entityMap|0|LINK|mutability|MUTABLE|url|http://code.google.com/apis/ajaxlanguage/documentation/#Translation^0|1F|J|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

do you have web access? i would assume that cannot be guaranteed, but Google has a language api that will detect the language you pass to it.
<a href="http://code.google.com/apis/ajaxlanguage/documentation/#Translation" rel="nofollow noreferrer">google language api</a>

blocks|key|1113531|text|不要使用RegEx和LINQ，它们比循环的字符串字符要慢。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1113532|Perfomance+test|offset|length|1113533|我的解决方案是：|1113534|private+static+bool+is_only_eng_letters_and_digits(string+str)
{
+++foreach+(char+ch+in+str)
+++{
++++++if+(!(ch+>=+'A'+&&+ch+<=+'Z')+&&+!(ch+>=+'a'+&&+ch+<=+'z')+&&+!(ch+>=+'0'+&&+ch+<=+'9'))
++++++{
+++++++++return+false;
++++++}
+++}
+++return+true;
}|code-block|syntax|javascript|1113535|entityMap|0|LINK|mutability|MUTABLE|url|https://dotnetfiddle.net/Qv61xu^0|0|0|F|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|V|8|@]|9|@$D|W|E|X|1|Y]]|A|$]]|$1|F|3|G|5|6|7|Z|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|10|8|@]|9|@]|A|$K|L]]|$1|M|3|-4|5|6|7|11|8|@]|9|@]|A|$]]]|N|$O|$5|P|Q|R|A|$S|T]]]]

Do not use RegEx and LINQ they are slower than the loop by characters of string

<a href="https://dotnetfiddle.net/Qv61xu" rel="nofollow noreferrer">Perfomance test</a>

My solution:

<pre><code>private static bool is_only_eng_letters_and_digits(string str)
{
 foreach (char ch in str)
 {
 if (!(ch &gt;= 'A' &amp;&amp; ch &lt;= 'Z') &amp;&amp; !(ch &gt;= 'a' &amp;&amp; ch &lt;= 'z') &amp;&amp; !(ch &gt;= '0' &amp;&amp; ch &lt;= '9'))
 {
 return false;
 }
 }
 return true;
}
</code></pre>

blocks|key|1328493|text|bool+onlyEnglishCharacters+=+!EnglishText.Any(a+=>+a+>+'~');|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1328494|看起来很便宜，但它对我很有效，合法而简单的答案。希望这对任何人都有帮助。|unstyled|1328495|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>bool onlyEnglishCharacters = !EnglishText.Any(a =&gt; a &gt; '~');
</code></pre>

Seems cheap, but it worked for me, legit easy answer.
Hope it helps anyone.

blocks|key|1113118|text|bool+AllAscii(string+str)
{+
+++return+!str.Any(c+=>+!Char.IsLetterOrDigit(c));
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1113119|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>bool AllAscii(string str)
{ 
 return !str.Any(c =&gt; !Char.IsLetterOrDigit(c));
}
</code></pre>

blocks|key|1113149|text|如下所示(如果你想控制输入)：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1113150|static+string+ReadLettersAndDigits()+{
++++StringBuilder+sb+=+new+StringBuilder();
++++ConsoleKeyInfo+keyInfo;
++++while+((keyInfo+=+Console.ReadKey(true)).Key+!=+ConsoleKey.Enter)+{
++++++++char+c+=+char.ToLower(keyInfo.KeyChar);
++++++++if+(('a'+<=+c+&&+c+<=+'z')+%7C%7C+char.IsDigit(c))+{
++++++++++++sb.Append(keyInfo.KeyChar);
++++++++++++Console.Write(c);
++++++++}
++++}
++++return+sb.ToString();
}|code-block|syntax|javascript|1113151|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|$]]

Something like this (if you want to control input):

<pre><code>static string ReadLettersAndDigits() {
 StringBuilder sb = new StringBuilder();
 ConsoleKeyInfo keyInfo;
 while ((keyInfo = Console.ReadKey(true)).Key != ConsoleKey.Enter) {
 char c = char.ToLower(keyInfo.KeyChar);
 if (('a' &lt;= c &amp;&amp; c &lt;= 'z') || char.IsDigit(c)) {
 sb.Append(keyInfo.KeyChar);
 Console.Write(c);
 }
 }
 return sb.ToString();
}
</code></pre>

blocks|key|1113242|text|如果我不想使用RegEx，只是为了提供另一种解决方案，你可以只检查每个字符的ASCII码，如果它在这个范围内，它要么是英文字母，要么是数字(这可能不是最好的解决方案)：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1113243|foreach+(char+ch+in+str.ToCharArray())+
{+
++++int+x+=+(int)char;
++++if+(x+>=+63+and+x+<=+126)+
++++{
+++++++//this+is+english+letter,+i.e.-+A,+B,+C,+a,+b,+c...
++++}
++++else+if(x+>=+48+and+x+<=+57)
++++{
+++++++//this+is+number
++++}
++++else
++++{
+++++++//this+is+something+diffrent
++++}

}+|code-block|syntax|javascript|1113244|完整ASCII表的http://en.wikipedia.org/wiki/ASCII。|offset|length|1113245|但我仍然认为，RegEx是最好的解决方案。|1113246|entityMap|0|LINK|mutability|MUTABLE|url|http://en.wikipedia.org/wiki/ASCII^0|0|0|9|Y|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@]|9|@$I|X|J|Y|1|Z]]|A|$]]|$1|K|3|L|5|6|7|10|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|11|8|@]|9|@]|A|$]]]|N|$O|$5|P|Q|R|A|$S|T]]]]

If i dont wnat to use RegEx, and just to provide an alternate solution, you can just check the ASCII code of each character and if it lies between that range, it would either be a english letter or a number (This might not be the best solution):

<pre><code>foreach (char ch in str.ToCharArray()) 
{ 
 int x = (int)char;
 if (x &gt;= 63 and x &lt;= 126) 
 {
 //this is english letter, i.e.- A, B, C, a, b, c...
 }
 else if(x &gt;= 48 and x &lt;= 57)
 {
 //this is number
 }
 else
 {
 //this is something diffrent
 }

} 
</code></pre>

<a href="http://en.wikipedia.org/wiki/ASCII" rel="nofollow noreferrer">http://en.wikipedia.org/wiki/ASCII</a> for full ASCII table.

But I still think, RegEx is the best solution.

blocks|key|1328435|text|我同意正则表达式answers。但是，您可以将其简化为"%5E\w%2B$“。\w是任何“单词字符”(如果使用非unicode字母表，则转换为a-zA-Z_0-9。我不知道你是否也想要下划线。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1328436|有关.net中正则表达式的更多信息，请访问：http://msdn.microsoft.com/en-us/library/ms972966.aspx#regexnet_topic8|offset|length|1328437|entityMap|0|LINK|mutability|MUTABLE|url|http://msdn.microsoft.com/en-us/library/ms972966.aspx#regexnet_topic8^0|0|M|1X|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|O|8|@]|9|@$D|P|E|Q|1|R]]|A|$]]|$1|F|3|-4|5|6|7|S|8|@]|9|@]|A|$]]]|G|$H|$5|I|J|K|A|$L|M]]]]

I agree with the Regular Expression answers. However, you could simplify it to just "^[\w]+$". \w is any "word character" (which translates to [a-zA-Z_0-9] if you use a non-unicode alphabet. I don't know if you want underscores as well.

More on regexes in .net here: <a href="http://msdn.microsoft.com/en-us/library/ms972966.aspx#regexnet_topic8" rel="nofollow noreferrer">http://msdn.microsoft.com/en-us/library/ms972966.aspx#regexnet_topic8</a>

blocks|key|1328523|text|正如许多人指出的那样，只有当字符串中有一个单词时，接受的答案才有效。由于没有覆盖字符串中多个单词甚至句子的情况的答案，因此代码如下：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1328524|stringToCheck.Any(x=>+char.IsLetter(x)+&&+!((int)x+>=+63+&&+(int)x+<=+126));|code-block|syntax|javascript|1328525|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|$]]

As many pointed out, accepted answer works only if there is a single word in the string. As there are no answers that cover the case of multiple words or even sentences in the string, here is the code:

<pre><code>stringToCheck.Any(x=&gt; char.IsLetter(x) &amp;&amp; !((int)x &gt;= 63 &amp;&amp; (int)x &lt;= 126));
</code></pre>

blocks|key|1113481|text|<?php
++++$string="हिन्दी";
++++$string="Manvendra+Rajpurohit";
++++echo+strlen($string);+echo+' ';
++++echo+mb_strlen($string,+'utf-8');
++++echo+' ';
++++if(strlen($string)+!=+mb_strlen($string,+'utf-8'))
++++{+
++++++++echo+"Please+enter+English+words+only:(";
++++}
++++else+{
++++++++echo+"OK,+English+Detected!";
++++}
?>|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1113482|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>&lt;?php
 $string="हिन्दी";
 $string="Manvendra Rajpurohit";
 echo strlen($string); echo '&lt;br&gt;';
 echo mb_strlen($string, 'utf-8');
 echo '&lt;br&gt;';
 if(strlen($string) != mb_strlen($string, 'utf-8'))
 { 
 echo "Please enter English words only:(";
 }
 else {
 echo "OK, English Detected!";
 }
?&gt;
</code></pre>

I read a string from the console. How do I make sure it only contains English characters and digits?

How do I verify that a string is in English?

我从控制台读取了一个字符串。如何确保它只包含英文字符和数字？

问如何验证字符串是否为英文？
EN

回答 11

Stack Overflow用户

Stack Overflow用户

Stack Overflow用户

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

问如何验证字符串是否为英文？EN

回答 11

Stack Overflow用户

Stack Overflow用户

Stack Overflow用户

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

问如何验证字符串是否为英文？
EN