blocks|key|3886832|text|假设在循环外不需要result，那么可以在循环内声明result：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3886833|for(+int+i=0;+i+<+sizeOfArray;+%2B%2Bi+)+{
++++double+result+=+transmogrify(+array[i]+);
++++...
}|code-block|syntax|javascript|3886834|entityMap^0|9|6|Q|6|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|$]]

Assuming you don't need <code>result</code> outside of the loop, you could declare <code>result</code> inside the loop thusly:

<pre><code>for( int i=0; i &lt; sizeOfArray; ++i ) {
 double result = transmogrify( array[i] );
 ...
}
</code></pre>

blocks|key|1192469|text|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1192470|我收到了一个警告，为result计算的值永远不会被使用，因为(理论上)可能不会选择if/else分支|blockquote|offset|length|style|CODE|1192471|1192472|1192473|这不可能是发出警告的原因，因为在if条件中也使用了result。即使没有任何分支被采用，仍然使用result来决定不应该采用它们。|1192474|entityMap^0|0|A|6|0|0|0|P|6|1C|6|0^^$0|@$1|2|3|-4|4|5|6|N|7|@]|8|@]|9|$]]|$1|A|3|B|4|C|6|O|7|@$D|P|E|Q|F|G]]|8|@]|9|$]]|$1|H|3|-4|4|5|6|R|7|@]|8|@]|9|$]]|$1|I|3|-4|4|5|6|S|7|@]|8|@]|9|$]]|$1|J|3|K|4|5|6|T|7|@$D|U|E|V|F|G]|$D|W|E|X|F|G]]|8|@]|9|$]]|$1|L|3|-4|4|5|6|Y|7|@]|8|@]|9|$]]]|M|$]]

<blockquote>
 I'm getting a warning that the value computed for <code>result</code> is never used because (theoretically) it's possible that none of the if/else branches will be selected
</blockquote>

That can't be the reason for the warning, because <code>result</code> is also used in the if conditions. Even if none of the branches are taken, <code>result</code> is still used to decide that they should not be taken.

blocks|key|667459|text|分别用DBL_MAX和DBL_MIN初始化myMin和myMax，并通过循环检查摆脱第一次。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|667460|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|$]]

Initialize myMin and myMax with DBL_MAX and DBL_MIN respectively and get rid of the first time through the loop check.

blocks|key|667360|text|我不认为发布的代码应该会产生错误，除非编译器正在做一些现象级的流分析。它当然可以用g%2B%2B编译，但我不确定g%2B%2B是否支持你得到的警告。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|667361|代码的以下改编保留了其结构，不会对g%2B%2B产生错误：|667362|int+main()+{
double+*+array;
double+result;
double+myMin;
double+myMax;

double+t(double);

//+Assume+array+is+initialized+properly...
for+(int+i+=+0;+i+<+10;+%2B%2Bi)+{
++++result+=+t(array[i]);
++++if+(i+==+0)+{
++++++++myMin+=+result;
++++++++myMax+=+result;
++++}
++++else+if+(result+<+myMin)+{
++++++++myMin+=+result;
++++}
++++else+if+(result+>+myMax)+{
++++++++myMax+=+result;
++++}
}|code-block|syntax|javascript|667363|}|667364|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|O|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

I don't think the code as posted should produce the error, unless the compiler is doing some phenomenal flow analysis. It certainly compiles OK with g++, but I'm not sure that g++ even supports the warning you are getting.

The following adaptation of your code, which preserves its structure, produces no error with g++:

<pre><code>int main() {
double * array;
double result;
double myMin;
double myMax;

double t(double);

// Assume array is initialized properly...
for (int i = 0; i &lt; 10; ++i) {
 result = t(array[i]);
 if (i == 0) {
 myMin = result;
 myMax = result;
 }
 else if (result &lt; myMin) {
 myMin = result;
 }
 else if (result &gt; myMax) {
 myMax = result;
 }
}
</code></pre>

}

blocks|key|1192437|text|result+=+[...]
if+(i+==+0)+{
++++[...+do+something+with+result+...]
}
else+if+(result+<+myMin)+{|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1192438|在if()的两个分支中，都使用了result。在第一种情况下，它被赋值给一个变量，在第二种情况下，它用于比较。所以编译器不应该发出警告。|unstyled|offset|length|style|CODE|1192439|我怀疑你可能误诊了这个问题。请您准确地说出错误信息是什么(复制-粘贴)。此外，请尝试发布您可以实际编译并给出警告的最小代码片段。(简单地尝试这样做可能会让您找到问题所在)|1192440|编辑:+transmogrify()有没有可能是一个在内部使用result的宏？|1192441|entityMap^0|0|G|6|0|0|V|6|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|R|8|@$G|S|H|T|I|J]]|9|@]|A|$]]|$1|K|3|L|5|F|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|F|7|V|8|@$G|W|H|X|I|J]]|9|@]|A|$]]|$1|O|3|-4|5|F|7|Y|8|@]|9|@]|A|$]]]|P|$]]

<pre><code>result = [...]
if (i == 0) {
 [... do something with result ...]
}
else if (result &lt; myMin) {
</code></pre>

In both branches of the if(), <code>result</code> is used. In the 1st case it's assigned to a variable, in the 2nd it's used in a comparison. So the compiler shouldn't warn.

I suspect you might have misdiagnosed the problem. Please can you say exactly what the error message is (copy-paste it). Also, please try to post the smallest piece of code you can that actually compiles and gives the warning? (Simply trying to do that will probably let you find the problem)

EDIT: Is it possible that transmogrify() is a macro that uses <code>result</code> internally?

blocks|key|4730216|text|在"if“语句之前：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4730217|result+=+0.0;|code-block|syntax|javascript|4730218|或其他值。在使用变量之前将其设置为某个值总是很好的形式。|4730219|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|$]]

Before the "if" statement:

<pre><code>result = 0.0;
</code></pre>

or some other value. It is always good form to set a variable to some value before using it.

blocks|key|4730249|text|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4730250|我得到了一个警告，为result计算的值永远不会被使用，因为(理论上)可能不会选择if/else分支，而且由于我们将所有警告都视为错误，因此无法编译。如何修复此代码以避免出现警告？我使用g%2B%2B作为我的编译器|blockquote|4730251|4730252|4730253|始终使用用于result的值。如果未赋值，则在比较器中使用它。因此，编译器是错误的。|4730254|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|-4|4|5|6|J|7|@]|8|@]|9|$]]|$1|A|3|B|4|C|6|K|7|@]|8|@]|9|$]]|$1|D|3|-4|4|5|6|L|7|@]|8|@]|9|$]]|$1|E|3|-4|4|5|6|M|7|@]|8|@]|9|$]]|$1|F|3|G|4|5|6|N|7|@]|8|@]|9|$]]|$1|H|3|-4|4|5|6|O|7|@]|8|@]|9|$]]]|I|$]]

<blockquote>
 I'm getting a warning that the value computed for result is never used because (theoretically) it's possible that none of the if/else branches will be selected, and since we treat all warnings as errors, this doesn't compile. How can I fix this code to avoid the warning? I'm using g++ for my compiler
</blockquote>

The value used for result is always used. If not assigned it's used in the comparator. Therefore the compiler is faulty.

blocks|key|1200012|text|一个快速的解决方案可能是展开第一次迭代，如下所示：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1200013|double+*+array;
double+result+=+transmogrify(array[0]);
double+myMin+=+result;
double+myMax+=+result;
int+i;

for+(i+=+1;+i+<+sizeOfArray;+%2B%2Bi)+{
++++result+=+transmogrify(array[i]);

++++if+(result+<+myMin)+{
++++++++myMin+=+result;
++++}

++++if+(result+>+myMax)+{
++++++++myMax+=+result;
++++}
}|code-block|syntax|javascript|1200014|编辑:我将在这方面做一点扩展。您没有提供任何关于sizeOfArray的详细信息，但我猜测它是一个带符号的整数类型。|1200015|我相信您误解了警告的原因，result可能未使用，因为sizeOfArray可能小于或等于零，而不是因为循环中的if..else子句。在上面的代码中，您需要小心处理这种情况(sizeOfArray+<=+0)的原因可能会更清楚一些，但在原始代码片段中也同样重要。|1200016|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|$]]

A quick solution might be to unroll the first iteration, like this:

<pre><code>double * array;
double result = transmogrify(array[0]);
double myMin = result;
double myMax = result;
int i;

for (i = 1; i &lt; sizeOfArray; ++i) {
 result = transmogrify(array[i]);

 if (result &lt; myMin) {
 myMin = result;
 }

 if (result &gt; myMax) {
 myMax = result;
 }
}
</code></pre>

EDIT: I'll expand a bit on this. You haven't given any detailed information on sizeOfArray, but my guess is that it's a signed integer type.

I believe you've misunderstood the cause of the warning, result might be unused because sizeOfArray might be less than or equal to zero, not because of the if..else clauses inside the loop. In the code above, it might be a bit clearer why you need careful handling of the case (sizeOfArray &lt;= 0), but it's equally important in the original code snippet as well.

blocks|key|4730086|text|删除第一个else只会影响循环中第一次运行的运行时间。我宁可把它去掉。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4730087|if+(i+==+0)+{
++++myMin+=+result;
++++myMax+=+result;
}
if+(result+<+myMin)+
++++myMin+=+result;
else+if+(result+>+myMax)+
++++myMax+=+result;|code-block|syntax|javascript|4730088|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|$]]

Removing the first else only impacts the running time of the first run through the loop. I'd eliminate it rather. 

<pre><code>if (i == 0) {
 myMin = result;
 myMax = result;
}
if (result &lt; myMin) 
 myMin = result;
else if (result &gt; myMax) 
 myMax = result;
</code></pre>

I have an array of doubles and need to do a calculation on that array and then find the min and max value that results from that calculation. Here is basically what I have:

<pre><code>double * array;
double result;
double myMin;
double myMax;

// Assume array is initialized properly...
for (int i = 0; i &lt; sizeOfArray; ++i) {
 result = transmogrify(array[i]);
 if (i == 0) {
 myMin = result;
 myMax = result;
 }
 else if (result &lt; myMin) {
 myMin = result;
 }
 else if (result &gt; myMax) {
 myMax = result;
 }
}
</code></pre>

I'm getting a warning that the value computed for <code>result</code> is never used, and since we treat all warnings as errors, this doesn't compile. How can I fix this code to avoid the warning? I'm using g++ for my compiler.

Here's the warning text:

<pre><code>cc1plus: warnings being treated as errors
foo.cc:&lt;lineno of transmogrify call&gt;: error: value computed is not used
</code></pre>

Edit: I don't understand the down votes, but I've got things working now. Thanks to everyone for taking the time to help me out.

How should I correct this code that causes "value computed not used" warning?

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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我有一个双精度数组，需要对该数组进行计算，然后找到该计算结果的最小值和最大值。这基本上就是我所拥有的：double * array;double result;double myMin;double myMax;// Assume array is initialized properly...for (int i = 0; i < sizeOfArray; ++i) { result =

问我应该如何纠正这个导致“值计算未使用”警告的代码？
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问我应该如何纠正这个导致“值计算未使用”警告的代码？
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