blocks|key|4496142|text|你就快做到了：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4496143|if+(buffer[i]+>+0x3f)
{
++++//+do+something
}|code-block|syntax|javascript|4496144|请注意，不需要将任何内容“转换”为十六进制-您可以直接比较字符或整数值，因为十六进制常量(如0x3f+)只是表示整数值的另一种方式。0x3f+==+63+(十进制)+==+ASCII+'?‘。|4496145|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|$]]

You're nearly there:

<pre><code>if (buffer[i] &gt; 0x3f)
{
 // do something
}
</code></pre>

Note that there is no need to "convert" anything to hex - you can just compare character or integer values directly, since a hex constant such as 0x3f is just another way of representing an integer value. 0x3f == 63 (decimal) == ASCII '?'.

blocks|key|4778196|text|是的，您可以：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4778197|+if++(buffer[i]+>+0x3F)|code-block|syntax|javascript|4778198|(请注意小写的x)。编辑它证明0X3F应该也能工作得很好，但我很想说它不是C程序员通常写的)。|offset|length|style|BOLD|CODE|4778199|entityMap^0|0|0|A|2|F|4|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|Q|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|R|8|@$I|S|J|T|K|L]|$I|U|J|V|K|M]]|9|@]|A|$]]|$1|N|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|O|$]]

Yes you can:

<pre><code> if (buffer[i] &gt; 0x3F)
</code></pre>

(note the lowercase x). Edit it turns out <code>0X3F</code> should work just as well, but I am tempted to say it is not what C programmers usually write).

blocks|key|4496247|text|计算机中的数字都是0和1。在基数10、基数16+(十六进制)或字符(如'a')中查看它们不会更改数字。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4496248|所以，与十六进制相比，你不需要做任何事情。|4496249|例如，如果您有|4496250|int+a+=+71;|code-block|syntax|javascript|4496251|那么以下两个语句是等价的：|4496252|if+(a+==+71)|4496253|和|4496254|if+(a+==+0x47)|4496255|entityMap^0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|V|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|W|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|X|8|@]|9|@]|A|$I|J]]|$1|K|3|L|5|6|7|Y|8|@]|9|@]|A|$]]|$1|M|3|N|5|H|7|Z|8|@]|9|@]|A|$I|J]]|$1|O|3|P|5|6|7|10|8|@]|9|@]|A|$]]|$1|Q|3|R|5|H|7|11|8|@]|9|@]|A|$I|J]]|$1|S|3|-4|5|6|7|12|8|@]|9|@]|A|$]]]|T|$]]

Numbers in the computer are all 0s and 1s. Looking at them in base 10, or base 16 (hex) , or as a character (such as 'a') doesn't change the number.

So, to compare with hex, you don't need to do anything.

For example, if you have

<pre><code>int a = 71;
</code></pre>

Then the following two statements are equivalent:

<pre><code>if (a == 71)
</code></pre>

and

<pre><code>if (a == 0x47)
</code></pre>

blocks|key|4778272|text|十六进制值并不是什么新的数据类型，它只是另一个数值方法，比如|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4778273|int+a=+10；|4778274|十六进制打印中的|4778275|printf("a+in+hex+value+%25x+",a);|code-block|syntax|javascript|4778276|输出为|offset|length|style|BOLD|4778277|a+in+hex+value+A|4778278|在if循环中|4778279|if(a+==+0xa)
++++do+something|4778280|十进制中的|4778281|printf("a+in+decimal+value+%25d+",a);|4778282|4778283|a+in+hex+value+10|4778284|4778285|if(a+==+10)
++++do+something|4778286|entityMap^0|0|0|0|0|0|3|0|0|0|6|0|0|0|3|0|0|0|3|0|0|0|6|0|0^^$0|@$1|2|3|4|5|6|7|18|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|19|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|1A|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|1B|8|@]|9|@]|A|$I|J]]|$1|K|3|L|5|6|7|1C|8|@$M|1D|N|1E|O|P]]|9|@]|A|$]]|$1|Q|3|R|5|H|7|1F|8|@]|9|@]|A|$I|J]]|$1|S|3|T|5|6|7|1G|8|@$M|1H|N|1I|O|P]]|9|@]|A|$]]|$1|U|3|V|5|H|7|1J|8|@]|9|@]|A|$I|J]]|$1|W|3|X|5|6|7|1K|8|@$M|1L|N|1M|O|P]]|9|@]|A|$]]|$1|Y|3|Z|5|H|7|1N|8|@]|9|@]|A|$I|J]]|$1|10|3|L|5|6|7|1O|8|@$M|1P|N|1Q|O|P]]|9|@]|A|$]]|$1|11|3|12|5|H|7|1R|8|@]|9|@]|A|$I|J]]|$1|13|3|T|5|6|7|1S|8|@$M|1T|N|1U|O|P]]|9|@]|A|$]]|$1|14|3|15|5|H|7|1V|8|@]|9|@]|A|$I|J]]|$1|16|3|-4|5|6|7|1W|8|@]|9|@]|A|$]]]|17|$]]

Hex values are nothing new data types its just another numberical methods like 

int a = 10; 

in Hex printing 

<pre><code>printf("a in hex value %x ",a);
</code></pre>

output is 

<pre><code>a in hex value A
</code></pre>

in if loop

<pre><code>if(a == 0xa)
 do something
</code></pre>

in decimal 

<pre><code>printf("a in decimal value %d ",a);
</code></pre>

output is 

<pre><code>a in hex value 10
</code></pre>

in if loop

<pre><code>if(a == 10)
 do something
</code></pre>

blocks|key|4496308|text|当比较字符和十六进制时，你必须小心：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4496309|Using+the+==+operator+to+compare+a+char+to+0x80+always+results+in+false?|offset|length|4496310|我推荐在C99中引入的这种语法，以确保|4496311|if+(buffer[i]+>+'\x3f')
{
++++//+do+something
}|code-block|syntax|javascript|4496312|它告诉编译器0x3f是一个char而不是int+(类型安全)，否则你很可能会在这个比较中看到问题。|4496313|事实上，clang编译器会警告你这一点：|4496314|常量128与类型为'char‘的表达式的比较始终为false+-Werror，-Wtautological常量-超出范围-compare|4496315|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/17844622/using-the-operator-to-compare-a-char-to-0x80-always-results-in-false^0|0|0|20|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|11|8|@]|9|@$D|12|E|13|1|14]]|A|$]]|$1|F|3|G|5|6|7|15|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|16|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|17|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|18|8|@]|9|@]|A|$]]|$1|Q|3|R|5|6|7|19|8|@]|9|@]|A|$]]|$1|S|3|-4|5|6|7|1A|8|@]|9|@]|A|$]]]|T|$U|$5|V|W|X|A|$Y|Z]]]]

When comparing char to hex you must be careful:

<a href="https://stackoverflow.com/questions/17844622/using-the-operator-to-compare-a-char-to-0x80-always-results-in-false">Using the == operator to compare a char to 0x80 always results in false?</a>

I would recommend this syntax introduced in C99 to be sure

<pre><code>if (buffer[i] &gt; '\x3f')
{
 // do something
}
</code></pre>

It tells the compiler that the 0x3f is a char rather than an int (type-safety), otherwise it is likely you will see issue with this comparison.

In fact clang compiler will warn you about this:

comparison of constant 128 with expression of type 'char' is always false [-Werror,-Wtautological-constant-out-of-range-compare]

I am working with hex values. Until now I know how to print hex values and also precision thing. Now I want to compare the hex values. For example I am reading data from a file into a char buffer. Now I want to compare the hex value of data in the buffer. Is there anything like this?

<pre><code>if hex(buffer[i]) &gt; 0X3F 
then
//do somthing
</code></pre>

How can I do this?

How to compare hex values using C?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我正在使用十六进制值。到目前为止，我知道如何打印十六进制值和精度的东西。现在我想比较十六进制值。例如，我正在将文件中的数据读取到字符缓冲区中。现在我想要比较缓冲区中数据的十六进制值。有像这样的东西吗？if  hex(buffer[i]) > 0X3F  then//do somthing我该怎么做呢？

问如何使用C比较十六进制值？
EN

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问如何使用C比较十六进制值？EN