blocks|key|791312|text|试试Character.getNumericValue(char)。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|791313|String+element+=+"el5";
int+x+=+Character.getNumericValue(element.charAt(2));
System.out.println("x="+%2B+x);|code-block|syntax|javascript|791314|产生：|791315|x=5|791316|getNumericValue(char)的优点在于，它还可以处理像"el٥"和"el५"这样的字符串，其中٥和५分别是东阿拉伯语和印地语/梵语中的数字5。|791317|entityMap|0|LINK|mutability|MUTABLE|url|http://download.oracle.com/javase/6/docs/api/java/lang/Character.html#getNumericValue(char))^0|2|V|2|V|0|0|0|0|0|0|L|Y|5|14|5|1I|1|1K|1|0^^$0|@$1|2|3|4|5|6|7|Y|8|@$9|Z|A|10|B|C]]|D|@$9|11|A|12|1|13]]|E|$]]|$1|F|3|G|5|H|7|14|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|15|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|16|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|17|8|@$9|18|A|19|B|C]|$9|1A|A|1B|B|C]|$9|1C|A|1D|B|C]|$9|1E|A|1F|B|C]|$9|1G|A|1H|B|C]]|D|@]|E|$]]|$1|Q|3|-4|5|6|7|1I|8|@]|D|@]|E|$]]]|R|$S|$5|T|U|V|E|$W|X]]]]

Try <a href="http://download.oracle.com/javase/6/docs/api/java/lang/Character.html#getNumericValue(char)" rel="noreferrer"><code>Character.getNumericValue(char)</code></a>.

<pre><code>String element = "el5";
int x = Character.getNumericValue(element.charAt(2));
System.out.println("x=" + x);
</code></pre>

produces:

<pre><code>x=5
</code></pre>

The nice thing about <code>getNumericValue(char)</code> is that it also works with strings like <code>"el٥"</code> and <code>"el५"</code> where <code>٥</code> and <code>५</code> are the digits 5 in Eastern Arabic and Hindi/Sanskrit respectively.

blocks|key|1005473|text|尝试以下操作：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1005474|str1="2345";
int+x=str1.charAt(2)-'0';
//here+x=4;|code-block|syntax|javascript|1005475|如果u减去char+'0'，则不需要知道ASCII值。|1005476|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|$]]

Try the following: 

<pre><code>str1="2345";
int x=str1.charAt(2)-'0';
//here x=4;
</code></pre>

if u subtract by char '0', the ASCII value needs not to be known.

blocks|key|791391|text|从性能的角度来看，这可能是最好的，但它很粗糙：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|791392|String+element+=+"el5";
String+s;
int+x+=+element.charAt(2)-'0';|code-block|syntax|javascript|791393|如果你假设你的字符是一个数字，并且只在总是使用Unicode的语言中工作，比如Java...|791394|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|$]]

That's probably the best from the performance point of view, but it's rough:

<pre><code>String element = "el5";
String s;
int x = element.charAt(2)-'0';
</code></pre>

It works if you assume your character is a digit, and only in languages always using Unicode, like Java...

blocks|key|1005563|text|通过简单地用char+'0‘(零)减去char+(数字’0‘到'9')，可以将char转换为int(0到9)，例如，'+5+'-'0’表示int+5。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1005564|String+str+=+"123";

int+a=str.charAt(1)-'0';|code-block|syntax|javascript|1005565|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|$]]

By simply subtracting by char '0'(zero) a char (of digit '0' to '9') can be converted into int(0 to 9), e.g., '5'-'0' gives int 5.

<pre><code>String str = "123";

int a=str.charAt(1)-'0';
</code></pre>

blocks|key|791468|text|String+a+=+"jklmn489pjro635ops";

int+sum+=+0;

String+num+=+"";

boolean+notFirst+=+false;

for+(char+c+:+a.toCharArray())+{

++++if+(Character.isDigit(c))+{
++++++++sum+=+sum+%2B+Character.getNumericValue(c);
++++++++System.out.print((notFirst?+"+%2B+"+:+"")+%2B+c);
++++++++notFirst+=+true;
++++}
}

System.out.println("+=+"+%2B+sum);|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|791469|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>String a = "jklmn489pjro635ops";

int sum = 0;

String num = "";

boolean notFirst = false;

for (char c : a.toCharArray()) {

 if (Character.isDigit(c)) {
 sum = sum + Character.getNumericValue(c);
 System.out.print((notFirst? " + " : "") + c);
 notFirst = true;
 }
}

System.out.println(" = " + sum);
</code></pre>

blocks|key|1005596|text|在0b1111中使用二进制AND：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1005597|String+element+=+"el5";

char+c+=+element.charAt(2);

System.out.println(c+&+0b1111);+//+=>+'5'+&+0b1111+=>+0b0011_0101+&+0b0000_1111+=>+5

//+'0'+&+0b1111+=>+0b0011_0000+&+0b0000_1111+=>+0
//+'1'+&+0b1111+=>+0b0011_0001+&+0b0000_1111+=>+1
//+'2'+&+0b1111+=>+0b0011_0010+&+0b0000_1111+=>+2
//+'3'+&+0b1111+=>+0b0011_0011+&+0b0000_1111+=>+3
//+'4'+&+0b1111+=>+0b0011_0100+&+0b0000_1111+=>+4
//+'5'+&+0b1111+=>+0b0011_0101+&+0b0000_1111+=>+5
//+'6'+&+0b1111+=>+0b0011_0110+&+0b0000_1111+=>+6
//+'7'+&+0b1111+=>+0b0011_0111+&+0b0000_1111+=>+7
//+'8'+&+0b1111+=>+0b0011_1000+&+0b0000_1111+=>+8
//+'9'+&+0b1111+=>+0b0011_1001+&+0b0000_1111+=>+9|code-block|syntax|javascript|1005598|entityMap^0|1|6|D|3|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|L|$]]

Using binary <code>AND</code> with <code>0b1111</code>: 

<pre><code>String element = "el5";

char c = element.charAt(2);

System.out.println(c &amp; 0b1111); // =&gt; '5' &amp; 0b1111 =&gt; 0b0011_0101 &amp; 0b0000_1111 =&gt; 5

// '0' &amp; 0b1111 =&gt; 0b0011_0000 &amp; 0b0000_1111 =&gt; 0
// '1' &amp; 0b1111 =&gt; 0b0011_0001 &amp; 0b0000_1111 =&gt; 1
// '2' &amp; 0b1111 =&gt; 0b0011_0010 &amp; 0b0000_1111 =&gt; 2
// '3' &amp; 0b1111 =&gt; 0b0011_0011 &amp; 0b0000_1111 =&gt; 3
// '4' &amp; 0b1111 =&gt; 0b0011_0100 &amp; 0b0000_1111 =&gt; 4
// '5' &amp; 0b1111 =&gt; 0b0011_0101 &amp; 0b0000_1111 =&gt; 5
// '6' &amp; 0b1111 =&gt; 0b0011_0110 &amp; 0b0000_1111 =&gt; 6
// '7' &amp; 0b1111 =&gt; 0b0011_0111 &amp; 0b0000_1111 =&gt; 7
// '8' &amp; 0b1111 =&gt; 0b0011_1000 &amp; 0b0000_1111 =&gt; 8
// '9' &amp; 0b1111 =&gt; 0b0011_1001 &amp; 0b0000_1111 =&gt; 9
</code></pre>

blocks|key|791625|text|String+element+=+"el5";
int+x+=+element.charAt(2)+-+48;|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|791626|从字符中减去ascii值'0‘=+48|unstyled|791627|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>String element = "el5";
int x = element.charAt(2) - 48;
</code></pre>

Subtracting ascii value of '0' = 48 from char

I just want to know if there's a better solution to parse a number from a character in a string (assuming that we know that the character at index n is a number).

<pre><code>String element = "el5";
String s;
s = ""+element.charAt(2);
int x = Integer.parseInt(s);

//result: x = 5
</code></pre>

(useless to say that it's just an example)

Java: parse int value from a char

Java

我只想知道是否有更好的解决方案来从字符串中的字符解析数字(假设我们知道索引n处的字符是一个数字)。String element = "el5";String s;s = ""+element.charAt(2);int x = Integer.parseInt(s);//result: x = 5(说这只是一个例子是无用的)

问Java:从字符解析int值
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回答 7

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