blocks|key|4644383|text|我认为最重要的原因是如果你选择unsigned+int，你可能会得到一些逻辑错误。实际上，您通常不需要unsigned+int的范围，使用int更安全。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4644384|entityMap^0|F|C|1F|C|1X|3|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]|$9|M|A|N|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|O|8|@]|D|@]|E|$]]]|G|$]]

I think the most important reason is if you choose <code>unsigned int</code>, you can get some logical errors. In fact, you often do not need the range of <code>unsigned int</code>, using <code>int</code> is safer.

blocks|key|137840|text|如果length也是int，那么您应该使用相同的整数类型，否则当您在比较语句中混合有符号和无符号类型时，会发生奇怪的事情。大多数编译器都会给你一个警告。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|137841|你可以继续问，为什么要签署length？好吧，那可能是历史了。|137842|此外，如果您决定反转循环，即|137843|for(int+i=length-1;i>=0+;i--)
{
+++//+do+stuff
}|code-block|syntax|javascript|137844|如果使用无符号整数，逻辑就会中断。|137845|entityMap^0|2|6|A|3|0|D|6|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]|$9|V|A|W|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|X|8|@$9|Y|A|Z|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|10|8|@]|D|@]|E|$]]|$1|J|3|K|5|L|7|11|8|@]|D|@]|E|$M|N]]|$1|O|3|P|5|6|7|12|8|@]|D|@]|E|$]]|$1|Q|3|-4|5|6|7|13|8|@]|D|@]|E|$]]]|R|$]]

If <code>length</code> is also <code>int</code>, then you should use the same integer type, otherwise weird things happen when you mix signed and unsigned types in a comparison statement. Most compilers will give you a warning.

You could go on to ask, why should <code>length</code> be signed? Well, that's probably historical.

Also, if you decide to reverse the loop, ie

<pre><code>for(int i=length-1;i&gt;=0 ;i--)
{
 // do stuff
}
</code></pre>

the logic breaks if you use unsigned ints.

blocks|key|137888|text|使用unsigned可能会引入难以发现的编程错误，通常最好使用带符号的int来避免这些错误。一个例子是当你决定向后迭代而不是向前迭代时，并编写以下代码：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|137889|for+(unsigned+i+=+5;+i+>=+0;+i--)+{
++++printf("%25d\n",+i);
}|code-block|syntax|javascript|137890|另一种是如果你在循环中做一些数学运算：|137891|for+(unsigned+i+=+0;+i+<+10;+i%2B%2B)+{
++++for+(unsigned+j+=+0;+j+<+10;+j%2B%2B)+{
++++++++if+(i+-+j+>=+4)+printf("%25d+%25d\n",+i,+j);
++++}
}|137892|使用unsigned会引入这些类型的bug的可能性，并且没有任何好处。|137893|entityMap^0|2|8|Z|3|0|0|0|0|2|8|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]|$9|V|A|W|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|X|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|Y|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|Z|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|10|8|@$9|11|A|12|B|C]]|D|@]|E|$]]|$1|Q|3|-4|5|6|7|13|8|@]|D|@]|E|$]]]|R|$]]

Using <code>unsigned</code> can introduce programming errors that are hard to spot, and it's usually better to use signed <code>int</code> just to avoid them. One example would be when you decide to iterate backwards rather than forwards and write this:

<pre><code>for (unsigned i = 5; i &gt;= 0; i--) {
 printf("%d\n", i);
}
</code></pre>

Another would be if you do some math inside the loop:

<pre><code>for (unsigned i = 0; i &lt; 10; i++) {
 for (unsigned j = 0; j &lt; 10; j++) {
 if (i - j &gt;= 4) printf("%d %d\n", i, j);
 }
}
</code></pre>

Using <code>unsigned</code> introduces the potential for these sorts of bugs, and there's not really any upside.

blocks|key|137949|text|这通常是懒惰或缺乏理解。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|137950|当值不应该是负数时，我总是使用unsigned+int。这也符合文档的目的，即指定正确的值应该是什么。|137951|IMHO，断言使用"int“比使用"unsigned+int”更安全是完全错误的，也是一种糟糕的编程实践。|137952|如果你使用过Ada或Pascal，你会习惯于使用更安全的做法，为数值指定特定的范围(例如，一个只能是1，2，3，4，5的整数)。|137953|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|L|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|M|8|@]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

It's generally laziness or lack of understanding.

I aways use unsigned int when the value should not be negative. That also serves the documentation purpose of specifying what the correct values should be.

IMHO, the assertion that it is safer to use "int" than "unsigned int" is simply wrong and a bad programming practice.

If you have used Ada or Pascal you'd be accustomed to using the even safer practice of specifying specific ranges for values (e.g., an integer that can only be 1, 2, 3, 4, 5).

blocks|key|4644655|text|这段小代码与用例相关，如果你调用一些向量元素，那么原型是整型的，但在c%2B%2B中有很多现代的方法来做这件事。对于(const+auto+&v+:+vec)+{}或迭代器，在一些计算中，如果没有减法/达到负数，你可以并且应该使用无符号(更好地解释预期的值范围)，有时这里发布的许多示例表明你实际上需要int，但事实是它都是关于用例和情况的，没有一个严格的规则适用于所有的用例，强制使用一个规则将有点愚蠢……|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4644656|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

this tiny code is usecase related, if you call some vector element then the prototype is int but there're much modern ways to do it in c++ eg. for(const auto &amp;v : vec) {} or iterators, in some calculcation if there's no substracting/reaching a negative number you can and should use unsigned (explains better the range of values expected), sometimes as many posted examples here shows you actually need int but the truth is it's all about usecase and situation, no one strict rule apply to all usecases and it would be kinda dumb to force one over...

In a lot of code examples, source code, libraries etc. I see the use of int when as far as I can see, an <code>unsigned int</code> would make much more sense.

One place I see this a lot is in <code>for</code> loops. See below example:

<pre><code>for(int i = 0; i &lt; length; i++)
{
 // Do Stuff
}
</code></pre>

Why on earth would you use an <code>int</code> rather than an <code>unsigned int</code>? Is it just laziness - people can't be bothered with typing <code>unsigned</code>?

C/C++ use of int or unsigned int

编译器

在许多代码示例、源代码、库等中，我看到了int的用法，据我所知，unsigned int会更有意义。我经常在for循环中看到这种情况。如下例所示：for(int i = 0; i < length; i++){ // Do Stuff}您到底为什么要使用int而不是unsigned int？这仅仅是懒惰吗?人们不...

问C/C++使用int或unsigned int
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