blocks|key|334032|text|您可以使用Integer(str)，并查看它是否会引发：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|334033|def+is_num?(str)
++!!Integer(str)
rescue+ArgumentError,+TypeError
++false
end|code-block|syntax|javascript|334034|应该指出的是，虽然这对于"01"确实会返回true，但对于"09"则不会，因为09不是有效的整数文本。如果这不是您想要的行为，您可以将10作为第二个参数添加到Integer，这样这个数字总是被解释为基数10。|334035|entityMap^0|5|C|0|0|C|4|T|4|13|2|1V|2|27|7|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|S|8|@$9|T|A|U|B|C]|$9|V|A|W|B|C]|$9|X|A|Y|B|C]|$9|Z|A|10|B|C]|$9|11|A|12|B|C]]|D|@]|E|$]]|$1|M|3|-4|5|6|7|13|8|@]|D|@]|E|$]]]|N|$]]

You can use <code>Integer(str)</code> and see if it raises:

<pre><code>def is_num?(str)
 !!Integer(str)
rescue ArgumentError, TypeError
 false
end
</code></pre>

It should be pointed out that while this does return true for <code>"01"</code>, it does not for <code>"09"</code>, simply because <code>09</code> would not be a valid integer literal. If that's not the behaviour you want, you can add <code>10</code> as a second argument to <code>Integer</code>, so the number is always interpreted as base 10.

blocks|key|3097881|text|好吧，这里有一个简单的方法：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3097882|class+String
++def+is_integer?
++++self.to_i.to_s+==+self
++end
end

>>+"12".is_integer?
=>+true
>>+"blah".is_integer?
=>+false|code-block|syntax|javascript|3097883|我不同意引发异常来转换字符串的解决方案-异常不是控制流，你最好用正确的方式来做。也就是说，我上面的解决方案没有处理非10进制的整数。因此，下面是不用求助于异常的方法：|3097884|++class+String
++++def+integer?+
++++++[++++++++++++++++++++++++++#+In+descending+order+of+likeliness:
++++++++/%5E[-%2B]?[1-9]([0-9]*)?$/,+#+decimal
++++++++/%5E0[0-7]%2B$/,+++++++++++++#+octal
++++++++/%5E0x[0-9A-Fa-f]%2B$/,++++++#+hexadecimal
++++++++/%5E0b[01]%2B$/++++++++++++++#+binary
++++++].each+do+%7Cmatch_pattern%7C
++++++++return+true+if+self+=~+match_pattern
++++++end
++++++return+false
++++end
++end|3097885|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|$]]

Well, here's the easy way:

<pre><code>class String
 def is_integer?
 self.to_i.to_s == self
 end
end

&gt;&gt; "12".is_integer?
=&gt; true
&gt;&gt; "blah".is_integer?
=&gt; false
</code></pre>

I don't agree with the solutions that provoke an exception to convert the string - exceptions are not control flow, and you might as well do it the right way. That said, my solution above doesn't deal with non-base-10 integers. So here's the way to do with without resorting to exceptions:

<pre><code> class String
 def integer? 
 [ # In descending order of likeliness:
 /^[-+]?[1-9]([0-9]*)?$/, # decimal
 /^0[0-7]+$/, # octal
 /^0x[0-9A-Fa-f]+$/, # hexadecimal
 /^0b[01]+$/ # binary
 ].each do |match_pattern|
 return true if self =~ match_pattern
 end
 return false
 end
 end
</code></pre>

blocks|key|334067|text|class+String
++def+integer?
++++Integer(self)
++++return+true
++rescue+ArgumentError
++++return+false
++end
end|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|334068|unstyled|334069|它没有前缀is_。我发现在问号方法上很愚蠢，我更喜欢"04".integer?，而不是"foo".is_integer?.|ordered-list-item|offset|length|style|CODE|334070|It使用sepp2k的合理解决方案，该解决方案被认为是"01"之类的。|334071|面向对象，耶。|334072|334073|entityMap^0|0|0|5|3|Q|D|17|H|0|R|4|0|0|0^^$0|@$1|2|3|4|5|6|7|T|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|U|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|V|8|@$I|W|J|X|K|L]|$I|Y|J|Z|K|L]|$I|10|J|11|K|L]]|9|@]|A|$]]|$1|M|3|N|5|H|7|12|8|@$I|13|J|14|K|L]]|9|@]|A|$]]|$1|O|3|P|5|H|7|15|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|E|7|16|8|@]|9|@]|A|$]]|$1|R|3|-4|5|E|7|17|8|@]|9|@]|A|$]]]|S|$]]

<pre><code>class String
 def integer?
 Integer(self)
 return true
 rescue ArgumentError
 return false
 end
end
</code></pre>

<ol>
<li>It isn't prefixed with <code>is_</code>. I find that silly on questionmark methods, I like <code>"04".integer?</code> a lot better than <code>"foo".is_integer?</code>.</li>
<li>It uses the sensible solution by sepp2k, which passes for <code>"01"</code> and such.</li>
<li>Object oriented, yay.</li>
</ol>

blocks|key|3310809|text|您可以使用正则表达式。以下是@janm建议的函数。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3310810|class+String
++++def+is_i?
+++++++!!(self+=~+/\A[-%2B]?[0-9]%2B\z/)
++++end
end|code-block|syntax|javascript|3310811|根据@wich的评论编辑的版本：|3310812|class+String
++++def+is_i?
+++++++/\A[-%2B]?\d%2B\z/+===+self
++++end
end|3310813|以防你只需要检查正数|3310814|++if+!/\A\d%2B\z/.match(string_to_check)
++++++#Is+not+a+positive+number
++else
++++++#Is+all+good+..continue
++end++|3310815|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]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

You can use regular expressions. Here is the function with @janm's suggestions.

<pre><code>class String
 def is_i?
 !!(self =~ /\A[-+]?[0-9]+\z/)
 end
end
</code></pre>

An edited version according to comment from @wich:

<pre><code>class String
 def is_i?
 /\A[-+]?\d+\z/ === self
 end
end
</code></pre>

In case you only need to check positive numbers 

<pre><code> if !/\A\d+\z/.match(string_to_check)
 #Is not a positive number
 else
 #Is all good ..continue
 end 
</code></pre>

blocks|key|337528|text|你可以做一个单行：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|337529|str+=+...
int+=+Integer(str)+rescue+nil

if+int
++int.times+{%7Ci%7C+p+i}
end|code-block|syntax|javascript|337530|甚至是|337531|int+=+Integer(str)+rescue+false|337532|根据您正在尝试执行的操作，您还可以直接使用begin+end+block+with+rescue子句：|337533|begin
++str+=+...
++i+=+Integer(str)

++i.times+do+%7Cj%7C
++++puts+j
++end
rescue+ArgumentError
++puts+"Not+an+int,+doing+something+else"
end|337534|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]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

You can do a one liner:

<pre><code>str = ...
int = Integer(str) rescue nil

if int
 int.times {|i| p i}
end
</code></pre>

or even

<pre><code>int = Integer(str) rescue false
</code></pre>

Depending on what you are trying to do you can also directly use a begin end block with rescue clause:

<pre><code>begin
 str = ...
 i = Integer(str)

 i.times do |j|
 puts j
 end
rescue ArgumentError
 puts "Not an int, doing something else"
end
</code></pre>

blocks|key|3097987|text|++def+isint(str)
++++return+!!(str+=~+/%5E[-%2B]?[1-9]([0-9]*)?$/)
++end|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|3097988|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> def isint(str)
 return !!(str =~ /^[-+]?[1-9]([0-9]*)?$/)
 end
</code></pre>

blocks|key|3098035|text|就我个人而言，我喜欢exception方法，尽管我会让它更简洁一些：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3098036|class+String
++def+integer?(str)
++++!!Integer(str)+rescue+false
++end
end|code-block|syntax|javascript|3098037|然而，正如其他人已经指出的那样，这不适用于八进制字符串。|3098038|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Personally I like the exception approach although I would make it a little more terse:

<pre><code>class String
 def integer?(str)
 !!Integer(str) rescue false
 end
end
</code></pre>

However, as others have already stated, this doesn't work with Octal strings.

blocks|key|3310912|text|"12".match(/%5E(\d)%2B$/)++++++#+true
"1.2".match(/%5E(\d)%2B$/)+++++#+false
"dfs2".match(/%5E(\d)%2B$/)++++#+false
"13422".match(/%5E(\d)%2B$/)+++#+true|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|3310913|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>"12".match(/^(\d)+$/) # true
"1.2".match(/^(\d)+$/) # false
"dfs2".match(/^(\d)+$/) # false
"13422".match(/^(\d)+$/) # true
</code></pre>

blocks|key|335255|text|Ruby2.4有Regexp#match?：(带有?)|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|335256|def+integer?(str)
++/\A[%2B-]?\d%2B\z/.match?+str
end|code-block|syntax|javascript|335257|对于老的Ruby版本，有Regexp#===。尽管通常应该避免直接使用case等式操作符，但它在这里看起来非常干净：|335258|def+integer?(str)
++/\A[%2B-]?\d%2B\z/+===+str
end

integer?+"123"++++#+true
integer?+"-123"+++#+true
integer?+"%2B123"+++#+true

integer?+"a123"+++#+false
integer?+"123b"+++#+false
integer?+"1\n2"+++#+false|335259|entityMap|0|LINK|mutability|MUTABLE|url|https://ruby-doc.org/core-2.4.0/Regexp.html#method-i-match-3F|1|http://ruby-doc.org/core-2.0.0/Regexp.html#method-i-3D-3D-3D^0|8|D|P|1|8|D|0|0|0|C|A|C|A|1|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@$9|Z|A|10|B|C]|$9|11|A|12|B|C]]|D|@$9|13|A|14|1|15]]|E|$]]|$1|F|3|G|5|H|7|16|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|17|8|@$9|18|A|19|B|C]]|D|@$9|1A|A|1B|1|1C]]|E|$]]|$1|M|3|N|5|H|7|1D|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|1E|8|@]|D|@]|E|$]]]|P|$Q|$5|R|S|T|E|$U|V]]|W|$5|R|S|T|E|$U|X]]]]

Ruby 2.4 has <a href="https://ruby-doc.org/core-2.4.0/Regexp.html#method-i-match-3F" rel="nofollow noreferrer"><code>Regexp#match?</code></a>: (with a <code>?</code>)

<pre><code>def integer?(str)
 /\A[+-]?\d+\z/.match? str
end
</code></pre>

For older Ruby versions, there's <a href="http://ruby-doc.org/core-2.0.0/Regexp.html#method-i-3D-3D-3D" rel="nofollow noreferrer"><code>Regexp#===</code></a>. And although direct use of the case equality operator should generally be avoided, it looks very clean here:

<pre><code>def integer?(str)
 /\A[+-]?\d+\z/ === str
end

integer? "123" # true
integer? "-123" # true
integer? "+123" # true

integer? "a123" # false
integer? "123b" # false
integer? "1\n2" # false
</code></pre>

blocks|key|3310957|text|最好、最简单的方法是使用Float|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3310958|val+=+Float+"234"+rescue+nil

Float+"234"+rescue+nil+#=>+234.0

Float+"abc"+rescue+nil+#=>+nil

Float+"234abc"+rescue+nil+#=>+nil

Float+nil+rescue+nil+#=>+nil

Float+""+rescue+nil+#=>+nil|code-block|syntax|javascript|3310959|Integer也不错，但它将为Integer+nil返回0|3310960|entityMap^0|C|5|0|0|0|7|F|B|S|1|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|S|8|@$9|T|A|U|B|C]|$9|V|A|W|B|C]|$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|M|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|N|$]]

The Best and Simple way is using <code>Float</code>

<pre><code>val = Float "234" rescue nil

Float "234" rescue nil #=&gt; 234.0

Float "abc" rescue nil #=&gt; nil

Float "234abc" rescue nil #=&gt; nil

Float nil rescue nil #=&gt; nil

Float "" rescue nil #=&gt; nil
</code></pre>

<code>Integer</code> is also good but it will return <code>0</code> for <code>Integer nil</code>

blocks|key|3310974|text|根据上面@rado的答案，还可以使用一个三元语句来强制返回真或假布尔值，而不使用双刘海。诚然，双重逻辑否定版本更简洁，但对于新手(如我)来说可能更难阅读。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3310975|class+String
++def+is_i?
+++++self+=~+/\A[-%2B]?[0-9]%2B\z/+?+true+:+false
++end
end|code-block|syntax|javascript|3310976|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|$]]

Expanding on @rado's answer above one could also use a ternary statement to force the return of true or false booleans without the use of double bangs. Granted, the double logical negation version is more terse, but probably harder to read for newcomers (like me).

<pre><code>class String
 def is_i?
 self =~ /\A[-+]?[0-9]+\z/ ? true : false
 end
end
</code></pre>

blocks|key|3310992|text|这可能并不适用于所有情况，简单地使用：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3310993|"12".to_i+++=>+12
"blah".to_i+=>+0|code-block|syntax|javascript|3310994|对一些人来说可能也是如此。|3310995|如果它是一个数字，而不是0，它将返回一个数字。如果它返回0，它要么是一个字符串，要么是0。|3310996|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]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

This might not be suitable for all cases simplely using:

<pre><code>"12".to_i =&gt; 12
"blah".to_i =&gt; 0
</code></pre>

might also do for some.

If it's a number and not 0 it will return a number. If it returns 0 it's either a string or 0.

blocks|key|335286|text|一种简单得多的方法是|type|unstyled|depth|inlineStyleRanges|entityRanges|data|335287|/(\D%2B)/.match('1221').nil?+#=>+true
/(\D%2B)/.match('1a221').nil?+#=>+false
/(\D%2B)/.match('01221').nil?+#=>+true|code-block|syntax|javascript|335288|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|$]]

A much simpler way could be 

<pre><code>/(\D+)/.match('1221').nil? #=&gt; true
/(\D+)/.match('1a221').nil? #=&gt; false
/(\D+)/.match('01221').nil? #=&gt; true
</code></pre>

blocks|key|334204|text|string.rb中的一个线条|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|334205|def+is_integer?;+true+if+Integer(self)+rescue+false+end|code-block|syntax|javascript|334206|entityMap^0|0|9|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

One liner in <code>string.rb</code>

<pre><code>def is_integer?; true if Integer(self) rescue false end
</code></pre>

blocks|key|332662|text|我不确定这个问题是不是被问到了，但对于任何偶然发现这篇文章的人来说，最简单的方法是：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|332663|var+=+"12"
var.is_a?(Integer)+#+returns+false
var.is_a?(String)+#+returns+true

var+=+12
var.is_a?(Integer)+#+returns+true
var.is_a?(String)+#+returns+false|code-block|syntax|javascript|332664|.is_a?可以处理任何对象。|offset|length|style|CODE|332665|entityMap^0|0|0|0|6|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@$I|R|J|S|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

I'm not sure if this was around when this question is asked but 
for anyone that stumbles across this post, the simplest way is:

<pre><code>var = "12"
var.is_a?(Integer) # returns false
var.is_a?(String) # returns true

var = 12
var.is_a?(Integer) # returns true
var.is_a?(String) # returns false
</code></pre>

<code>.is_a?</code> will work with any object.

blocks|key|3311129|text|我更喜欢：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3311130|config/initializers/string.rb+.rb|3311131|class+String
++def+number?
++++Integer(self).is_a?(Integer)
++rescue+ArgumentError,+TypeError
++++false
++end
end|code-block|syntax|javascript|3311132|然后：|3311133|[218]+pry(main)>+"123123123".number?
=>+true
[220]+pry(main)>+"123+123+123".gsub(/+/,+'').number?
=>+true
[222]+pry(main)>+"123+123+123".number?
=>+false|3311134|或查看电话号码：|3311135|"%2B34+123+456+789+2".gsub(/+/,+'').number?|3311136|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]]|$1|I|3|J|5|6|7|V|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|W|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|X|8|@]|9|@]|A|$]]|$1|O|3|P|5|F|7|Y|8|@]|9|@]|A|$G|H]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

I prefer: 

config/initializers/string.rb

<pre><code>class String
 def number?
 Integer(self).is_a?(Integer)
 rescue ArgumentError, TypeError
 false
 end
end
</code></pre>

and then: 

<pre><code>[218] pry(main)&gt; "123123123".number?
=&gt; true
[220] pry(main)&gt; "123 123 123".gsub(/ /, '').number?
=&gt; true
[222] pry(main)&gt; "123 123 123".number?
=&gt; false
</code></pre>

or check phone number: 

<pre><code>"+34 123 456 789 2".gsub(/ /, '').number?
</code></pre>

blocks|key|3311199|text|对于更一般的情况(包括带小数点的数字)，您可以尝试以下方法：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3311200|def+number?(obj)
++obj+=+obj.to_s+unless+obj.is_a?+String
++/\A[%2B-]?\d%2B(\.[\d]%2B)?\z/.match(obj)
end|code-block|syntax|javascript|3311201|您可以在irb会话中测试此方法：|3311202|(irb)
>>+number?(7)
=>+#<MatchData+"7"+1:nil>
>>+!!number?(7)
=>+true
>>+number?(-Math::PI)
=>+#<MatchData+"-3.141592653589793"+1:".141592653589793">
>>+!!number?(-Math::PI)
=>+true
>>+number?('hello+world')
=>+nil
>>+!!number?('hello+world')
=>+false|3311203|有关此处涉及的正则表达式的详细解释，请查看this+blog+article+:)|offset|length|3311204|entityMap|0|LINK|mutability|MUTABLE|url|https://medium.com/@Taiga/number-validation-with-regex-ruby-393954e46797#.5m579y9t2^0|0|0|0|0|L|H|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Y|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|Z|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|10|8|@]|9|@$M|11|N|12|1|13]]|A|$]]|$1|O|3|-4|5|6|7|14|8|@]|9|@]|A|$]]]|P|$Q|$5|R|S|T|A|$U|V]]]]

For more generalised cases (including numbers with decimal point),
you can try the following method:

<pre><code>def number?(obj)
 obj = obj.to_s unless obj.is_a? String
 /\A[+-]?\d+(\.[\d]+)?\z/.match(obj)
end
</code></pre>

You can test this method in an irb session:

<pre><code>(irb)
&gt;&gt; number?(7)
=&gt; #&lt;MatchData "7" 1:nil&gt;
&gt;&gt; !!number?(7)
=&gt; true
&gt;&gt; number?(-Math::PI)
=&gt; #&lt;MatchData "-3.141592653589793" 1:".141592653589793"&gt;
&gt;&gt; !!number?(-Math::PI)
=&gt; true
&gt;&gt; number?('hello world')
=&gt; nil
&gt;&gt; !!number?('hello world')
=&gt; false
</code></pre>

For a detailed explanation of the regex involved here, check out <a href="https://medium.com/@Taiga/number-validation-with-regex-ruby-393954e46797#.5m579y9t2" rel="nofollow">this blog article</a> :)

blocks|key|337648|text|这是我的解决方案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|337649|#+/initializers/string.rb
class+String
++IntegerRegex+=+/%5E(\d)%2B$/

++def+integer?
++++!!self.match(IntegerRegex)
++end
end

#+any_model_or_controller.rb
'12345'.integer?+#+true
'asd34'.integer?+#+false|code-block|syntax|javascript|337650|下面是它的工作原理：|337651|用于在任何字符串中查找数字的|337652|/%5E(\d)%2B$/is正则表达式。您可以在http://rubular.com/.|unordered-list-item|offset|length|style|CODE|337653|We测试正则表达式和结果，将其保存在一个常量中，以避免每次我们在method.|337654|integer?中使用它时不必要的内存分配。false.|337655|match是一个查询方法，它应该返回true，或者nil.|337656|!!是一个在字符串上的方法，该方法根据参数中给定的正则表达式匹配出现的内容，并返回匹配值，或者IntegerRegex将match方法的结果转换为等效的布尔值。|337657|和声明现有String类中的方法是简单的修补，它不会更改现有字符串功能中的任何内容，而只是在任何字符串对象上添加另一个名为integer?的方法。|337658|337659|entityMap|0|LINK|mutability|MUTABLE|url|http://rubular.com/^0|0|0|0|0|0|9|L|J|0|0|0|0|8|M|5|0|0|5|I|4|P|3|0|0|2|1B|C|1O|5|0|5|6|1P|8|0|0^^$0|@$1|2|3|4|5|6|7|1A|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|1B|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|1C|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|1D|8|@]|9|@]|A|$]]|$1|K|3|L|5|M|7|1E|8|@$N|1F|O|1G|P|Q]]|9|@$N|1H|O|1I|1|1J]]|A|$]]|$1|R|3|S|5|M|7|1K|8|@]|9|@]|A|$]]|$1|T|3|U|5|M|7|1L|8|@$N|1M|O|1N|P|Q]|$N|1O|O|1P|P|Q]]|9|@]|A|$]]|$1|V|3|W|5|M|7|1Q|8|@$N|1R|O|1S|P|Q]|$N|1T|O|1U|P|Q]|$N|1V|O|1W|P|Q]]|9|@]|A|$]]|$1|X|3|Y|5|M|7|1X|8|@$N|1Y|O|1Z|P|Q]|$N|20|O|21|P|Q]|$N|22|O|23|P|Q]]|9|@]|A|$]]|$1|Z|3|10|5|M|7|24|8|@$N|25|O|26|P|Q]|$N|27|O|28|P|Q]]|9|@]|A|$]]|$1|11|3|-4|5|6|7|29|8|@]|9|@]|A|$]]|$1|12|3|-4|5|6|7|2A|8|@]|9|@]|A|$]]]|13|$14|$5|15|16|17|A|$18|19]]]]

Here's my solution:

<pre><code># /initializers/string.rb
class String
 IntegerRegex = /^(\d)+$/

 def integer?
 !!self.match(IntegerRegex)
 end
end

# any_model_or_controller.rb
'12345'.integer? # true
'asd34'.integer? # false
</code></pre>

And here's how it works:

<ul>
<li><code>/^(\d)+$/</code>is regex expression for finding digits in any string. You can test your regex expressions and results at <a href="http://rubular.com/" rel="nofollow noreferrer">http://rubular.com/</a>.</li>
<li>We save it in a constant <code>IntegerRegex</code> to avoid unnecessary memory allocation everytime we use it in the method.</li>
<li><code>integer?</code> is an interrogative method which should return <code>true</code> or <code>false</code>.</li>
<li><code>match</code> is a method on string which matches the occurrences as per the given regex expression in argument and return the matched values or <code>nil</code>.</li>
<li><code>!!</code> converts the result of <code>match</code> method into equivalent boolean.</li>
<li>And declaring the method in existing <code>String</code> class is monkey patching, which doesn't change anything in existing String functionalities, but just adds another method named <code>integer?</code> on any String object. </li>
</ul>

blocks|key|335381|text|Ruby2.6.0启用了casting+to+an+integer+without+raising+an+exception，如果转换失败，将返回nil。由于Ruby语言中false的行为很像nil，你可以很容易地检查一个整数，如下所示：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|335382|if+Integer(my_var,+exception:+false)
++#+do+something+if+my_var+can+be+cast+to+an+integer
end|code-block|syntax|javascript|335383|entityMap|0|LINK|mutability|MUTABLE|url|https://rubyreferences.github.io/rubychanges/2.6.html#numeric-methods-have-exception-argument^0|21|3|2E|5|2O|3|C|1E|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]|$9|V|A|W|B|C]|$9|X|A|Y|B|C]]|D|@$9|Z|A|10|1|11]]|E|$]]|$1|F|3|G|5|H|7|12|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|13|8|@]|D|@]|E|$]]]|L|$M|$5|N|O|P|E|$Q|R]]]]

Ruby 2.6.0 enables <a href="https://rubyreferences.github.io/rubychanges/2.6.html#numeric-methods-have-exception-argument" rel="noreferrer">casting to an integer without raising an exception</a>, and will return <code>nil</code> if the cast fails. And since <code>nil</code> mostly behaves like <code>false</code> in Ruby, you can easily check for an integer like so:

<pre><code>if Integer(my_var, exception: false)
 # do something if my_var can be cast to an integer
end
</code></pre>

blocks|key|3311305|text|我喜欢以下几点，直截了当：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3311306|def+is_integer?(str)
++str.to_i+!=+0+%7C%7C+str+==+'0'+%7C%7C+str+==+'-0'
end

is_integer?('123')
=>+true

is_integer?('sdf')
=>+false

is_integer?('-123')
=>+true

is_integer?('0')
=>+true

is_integer?('-0')
=>+true|code-block|syntax|javascript|3311307|尽管如此，还是要小心：|offset|length|style|BOLD|3311308|is_integer?('123sdfsdf')
=>+true|3311309|entityMap^0|0|0|5|6|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]]|$1|G|3|H|5|6|7|S|8|@$I|T|J|U|K|L]]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

I like the following, straight forward:

<pre class="lang-rb prettyprint-override"><code>def is_integer?(str)
 str.to_i != 0 || str == '0' || str == '-0'
end

is_integer?('123')
=&gt; true

is_integer?('sdf')
=&gt; false

is_integer?('-123')
=&gt; true

is_integer?('0')
=&gt; true

is_integer?('-0')
=&gt; true
</code></pre>

Careful though:

<pre class="lang-rb prettyprint-override"><code>is_integer?('123sdfsdf')
=&gt; true
</code></pre>

I need a function, <code>is_an_integer</code>, where

<ul>
<li><code>"12".is_an_integer?</code> returns true.</li>
<li><code>"blah".is_an_integer?</code> returns false.</li>
</ul>

How can I do this in Ruby? I would write a regex but I'm assuming there is a helper for this that I am not aware of.

How to test if a string is basically an integer in quotes using Ruby

Ruby语言

我需要一个函数，is_an_integer，其中"12".is_an_integer?返回true."blah".is_an_integer?返回false。我如何在Ruby中做到这一点？我会写一个正则表达式，但我假设有一个我不知道的帮助器。

问如何使用Ruby测试字符串是否基本上是用引号括起来的整数
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