blocks|key|1570646|text|可以，请使用以下代码：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1570647|stopAngle+=+Convert.ToDecimal(159.9);
startAngle+=+Convert.ToDecimal(355.87);|code-block|syntax|javascript|1570648|对于任意值，这个问题就更难了。:-)|1570649|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|$]]

Yes, use this code:

<pre><code>stopAngle = Convert.ToDecimal(159.9);
startAngle = Convert.ToDecimal(355.87);
</code></pre>

The problem is harder for arbitrary values. :-)

blocks|key|1355689|text|int+a+=+4,+b+=+6;
a+%5E=+b+%5E=+a+%5E=+b;|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1355690|适用于所有类型，包括字符串和浮点数。|unstyled|1355691|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>int a = 4, b = 6;
a ^= b ^= a ^= b;
</code></pre>

Works for all types including strings and floats.

blocks|key|1570882|text|BenAlabaster展示了一种进行变量切换的实用方法，但不需要try-catch子句。这段代码就足够了。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1570883|static+void+Swap<T>(ref+T+x,+ref+T+y)
{
+++++T+t+=+y;
+++++y+=+x;
+++++x+=+t;
}|code-block|syntax|javascript|1570884|用法如图所示：|1570885|float+startAngle+=+159.9F
float+stopAngle+=+355.87F
Swap(ref+startAngle,+ref+stopAngle);|1570886|您还可以使用扩展方法：|1570887|static+class+SwapExtension
{
++++public+static+T+Swap<T>(this+T+x,+ref+T+y)
++++{
++++++++T+t+=+y;
++++++++y+=+x;
++++++++return+t;
++++}
}|1570888|像这样使用它：|1570889|float+startAngle+=+159.9F;
float+stopAngle+=+355.87F;
startAngle+=+startAngle.Swap(ref+stopAngle);|1570890|这两种方法都在方法中使用临时变量，但在进行交换时不需要临时变量。|1570891|entityMap^0|0|0|0|0|0|0|0|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]]|$1|K|3|L|5|6|7|10|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|11|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|12|8|@]|9|@]|A|$]]|$1|Q|3|R|5|D|7|13|8|@]|9|@]|A|$E|F]]|$1|S|3|T|5|6|7|14|8|@]|9|@]|A|$]]|$1|U|3|-4|5|6|7|15|8|@]|9|@]|A|$]]]|V|$]]

BenAlabaster showed a practical way of doing a variable switch, but the try-catch clause is not needed. This code is enough.

<pre><code>static void Swap&lt;T&gt;(ref T x, ref T y)
{
 T t = y;
 y = x;
 x = t;
}
</code></pre>

The usage is the same as he shown:

<pre><code>float startAngle = 159.9F
float stopAngle = 355.87F
Swap(ref startAngle, ref stopAngle);
</code></pre>

You could also use an extension method:

<pre><code>static class SwapExtension
{
 public static T Swap&lt;T&gt;(this T x, ref T y)
 {
 T t = y;
 y = x;
 return t;
 }
}
</code></pre>

Use it like this:

<pre><code>float startAngle = 159.9F;
float stopAngle = 355.87F;
startAngle = startAngle.Swap(ref stopAngle);
</code></pre>

Both ways uses a temporary variable in the method, but you don't need the temporary variable where you do the swapping.

blocks|key|1570552|text|不是在C#中。在本机代码中，您可能能够使用三重XOR交换技巧，但在高级类型安全语言中则不能。(不管怎样，我听说在许多常见的CPU架构中，XOR技巧实际上比使用临时变量要慢。)|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1570553|您应该只使用临时变量。你没有理由不使用它；它并不是供应有限的。|1570554|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

Not in C#. In native code you might be able to use the triple-XOR swap trick, but not in a high level type-safe language. (Anyway, I've heard that the XOR trick actually ends up being slower than using a temporary variable in many common CPU architectures.)

You should just use a temporary variable. There's no reason you can't use one; it's not like there's a limited supply.

blocks|key|1356468|text|在C#+7中：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1356469|(startAngle,+stopAngle)+=+(stopAngle,+startAngle);|code-block|syntax|javascript|1356470|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|$]]

In C# 7:

<pre><code>(startAngle, stopAngle) = (stopAngle, startAngle);
</code></pre>

blocks|key|1570736|text|为了完整起见，这里是二进制XOR交换：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1570737|int+x+=+42;
int+y+=+51236;
x+%5E=+y;
y+%5E=+x;
x+%5E=+y;|code-block|syntax|javascript|1570738|这适用于所有原子对象/引用，因为它直接处理字节，但可能需要一个不安全的上下文才能处理小数或指针(如果您觉得非常扭曲)。在某些情况下，它也可能比temp变量慢。|1570739|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|$]]

For completeness, here is the binary XOR swap:

<pre><code>int x = 42;
int y = 51236;
x ^= y;
y ^= x;
x ^= y;
</code></pre>

This works for all atomic objects/references, as it deals directly with the bytes, but may require an unsafe context to work on decimals or, if you're feeling really twisted, pointers. And it may be slower than a temp variable in some circumstances as well.

blocks|key|1355792|text|如果可以从使用decimal改为使用double，则可以使用Interlocked类。据推测，这将是交换性能变量的好方法。它的可读性也比XOR略高一些。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1355793|var+startAngle+=+159.9d;
var+stopAngle+=+355.87d;
stopAngle+=+Interlocked.Exchange(ref+startAngle,+stopAngle);|code-block|syntax|javascript|1355794|Msdn:+Interlocked.Exchange+Method+(Double,+Double)|1355795|entityMap|0|LINK|mutability|MUTABLE|url|http://msdn.microsoft.com/en-us/library/3sh52ebc.aspx^0|7|7|I|6|U|B|0|0|0|1E|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|11|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|12|8|@]|D|@$9|13|A|14|1|15]]|E|$]]|$1|M|3|-4|5|6|7|16|8|@]|D|@]|E|$]]]|N|$O|$5|P|Q|R|E|$S|T]]]]

If you can change from using <code>decimal</code> to <code>double</code> you can use the <code>Interlocked</code> class.
Presumably this will be a good way of swapping variables performance wise. Also slightly more readable than XOR.

<pre><code>var startAngle = 159.9d;
var stopAngle = 355.87d;
stopAngle = Interlocked.Exchange(ref startAngle, stopAngle);
</code></pre>

<a href="http://msdn.microsoft.com/en-us/library/3sh52ebc.aspx" rel="noreferrer">Msdn: Interlocked.Exchange Method (Double, Double)</a>

blocks|key|1571392|text|在C#+7中，您可以使用元组解构在一行中实现所需的交换，并且清楚地知道发生了什么。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1571393|decimal+startAngle+=+Convert.ToDecimal(159.9);
decimal+stopAngle+=+Convert.ToDecimal(355.87);

(startAngle,+stopAngle)+=+(stopAngle,+startAngle);|code-block|syntax|javascript|1571394|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|$]]

With C# 7, you can use tuple deconstruction to achieve the desired swap in one line, and it's clear what's going on. 

<pre><code>decimal startAngle = Convert.ToDecimal(159.9);
decimal stopAngle = Convert.ToDecimal(355.87);

(startAngle, stopAngle) = (stopAngle, startAngle);
</code></pre>

blocks|key|1355625|text|a+=+a+%2B+b
b+=+a+-+b
a+=+a+-+b|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1355626|َ|unstyled|1355627|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>a = a + b
b = a - b
a = a - b
</code></pre>

َ

blocks|key|1355466|text|对于二进制类型，你可以使用这个时髦的技巧：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1355467|a+%25=+b+%25=+a+%25=+b;|code-block|syntax|javascript|1355468|只要a和b不是完全相同的变量(例如，同一个内存的别名)，它就可以工作。|1355469|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|$]]

For binary types you can use this funky trick:

<pre><code>a %= b %= a %= b;
</code></pre>

As long as a and b are not the exact same variable (e.g. aliases for the same memory) it works.

blocks|key|1355918|text|我希望这能有所帮助..。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1355919|using+System;

public+class+Program
{
++++public+static+void+Main()
++++{
++++++++int+a+=+1234;
++++++++int+b+=+4321;

++++++++Console.WriteLine("Before:+a+{0}+and+b+{1}",+a,+b);

++++++++b+=+b+-+a;
++++++++a+=+a+%2B+b;
++++++++b+=+a+-+b;

++++++++Console.WriteLine("After:+a+{0}+and+b+{1}",+a,+b);
++++}
}|code-block|syntax|javascript|1355920|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|$]]

I hope this might help...

<pre><code>using System;

public class Program
{
 public static void Main()
 {
 int a = 1234;
 int b = 4321;

 Console.WriteLine("Before: a {0} and b {1}", a, b);

 b = b - a;
 a = a + b;
 b = a - b;

 Console.WriteLine("After: a {0} and b {1}", a, b);
 }
}
</code></pre>

blocks|key|1355816|text|startAngle+=+(startAngle+%2B+stopAngle)+-+(stopAngle+=+startAngle);|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1355817|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>startAngle = (startAngle + stopAngle) - (stopAngle = startAngle);
</code></pre>

blocks|key|1356042|text|我们可以通过一个简单的技巧做到这一点。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1356043|a+=+20;
b+=+30;
a+=+a%2Bb;+//+add+both+the+number+now+a+has+value+50
b+=+a-b;+//+here+we+are+extracting+one+number+from+the+sum+by+sub
a+=+a-b;+//+the+number+so+obtained+in+above+help+us+to+fetch+the+alternate+number+from+sum
System.out.print("swapped+numbers+are+a+=+"%2B+a%2B"b+=+"%2B+b);|code-block|syntax|javascript|1356044|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|$]]

we can do that by doing a simple trick

<pre><code>a = 20;
b = 30;
a = a+b; // add both the number now a has value 50
b = a-b; // here we are extracting one number from the sum by sub
a = a-b; // the number so obtained in above help us to fetch the alternate number from sum
System.out.print("swapped numbers are a = "+ a+"b = "+ b);
</code></pre>

blocks|key|1571490|text|如果你想交换2个字符串变量：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1571491|a+=+(a%2Bb).Substring((b=a).Length);|code-block|syntax|javascript|1571492|相应的帮助器方法：|1571493|public+static+class+Foo+{
++++public+static+void+SwapString+(ref+string+a,+ref+string+b)+{
+++++++a+=+(a%2Bb).Substring((b=a).Length);
++++}
}|1571494|用法则为：|1571495|string+a="Test+1";
string+b="Test+2";
Foo.SwapString(a,+b);|1571496|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|$]]

If you want to swap 2 string variables:

<pre><code>a = (a+b).Substring((b=a).Length);
</code></pre>

An helper method accordingly:

<pre><code>public static class Foo {
 public static void SwapString (ref string a, ref string b) {
 a = (a+b).Substring((b=a).Length);
 }
}
</code></pre>

Usage would be then:

<pre><code>string a="Test 1";
string b="Test 2";
Foo.SwapString(a, b);
</code></pre>

blocks|key|1356000|text|下面是另一种方法：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1356001|decimal+a+=+159.9m;
decimal+b+=+355.87m;

a+=+b+%2B+(b+=+a)+-+b;|code-block|syntax|javascript|1356002|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|$]]

Here another approach in one line:

<pre><code>decimal a = 159.9m;
decimal b = 355.87m;

a = b + (b = a) - b;
</code></pre>

blocks|key|1571437|text|下面是一些交换两个变量的不同过程|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1571438|//process+one
a=b%2Ba;
b=a-b;
a=a-b;
printf("a=+%25d++b=++%25d",a,b);

//process+two
a=5;
b=10;
a=a%2Bb-(b=a);
printf("\na=+%25d++b=++%25d",a,b);

//process+three
a=5;
b=10;
a=a%5Eb;
b=a%5Eb;
a=b%5Ea;
printf("\na=+%25d++b=++%25d",a,b);

//process+four
a=5;
b=10;
a=b-~a-1;
b=a%2B~b%2B1;
a=a%2B~b%2B1;
printf("\na=+%25d++b=++%25d",a,b);|code-block|syntax|javascript|1571439|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|$]]

Here is some different process to swap two variables 

<pre><code>//process one
a=b+a;
b=a-b;
a=a-b;
printf("a= %d b= %d",a,b);

//process two
a=5;
b=10;
a=a+b-(b=a);
printf("\na= %d b= %d",a,b);

//process three
a=5;
b=10;
a=a^b;
b=a^b;
a=b^a;
printf("\na= %d b= %d",a,b);

//process four
a=5;
b=10;
a=b-~a-1;
b=a+~b+1;
a=a+~b+1;
printf("\na= %d b= %d",a,b);
</code></pre>

blocks|key|1571672|text|只是为了回答|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1571673|++++++++var+a+=+10;
++++++++var+b+=+20;

++++++++var+c+=+new+int[]+{+a,+b+};

++++++++a+=+c[1];
++++++++b+=+c[0];|code-block|syntax|javascript|1571674|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|$]]

just for Answering
<pre><code> var a = 10;
 var b = 20;

 var c = new int[] { a, b };

 a = c[1];
 b = c[0];
</code></pre>

blocks|key|1355762|text|var+a+=+15;
var+b+=+-214;
a+=+b+%7C+!(b+=+a);|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1355763|这很好用。|unstyled|1355764|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>var a = 15;
var b = -214;
a = b | !(b = a);
</code></pre>

This works great.

blocks|key|1571028|text|交换两个变量的非常简单的代码：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1571029|static+void+Main(string[]+args)
{
++++Console.WriteLine("Prof.Owais+ahmed");
++++Console.WriteLine("Swapping+two+variables");

++++Console.WriteLine("Enter+your+first+number+");
++++int+x+=+Convert.ToInt32(Console.ReadLine());

++++Console.WriteLine("Enter+your+first+number+");
++++int+y+=+Convert.ToInt32(Console.ReadLine());

++++Console.WriteLine("your+vlaue+of+x+is="%2Bx%2B"\nyour+value+of+y+is="%2By);

++++int+z+=+x;
++++x+=+y;
++++y+=+z;

++++Console.WriteLine("after+Swapping+value+of+x+is="%2Bx%2B"/nyour+value+of+y+is="%2By);
++++Console.ReadLine();
}|code-block|syntax|javascript|1571030|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|$]]

Very simple code for swapping two variables:

<pre><code>static void Main(string[] args)
{
 Console.WriteLine("Prof.Owais ahmed");
 Console.WriteLine("Swapping two variables");

 Console.WriteLine("Enter your first number ");
 int x = Convert.ToInt32(Console.ReadLine());

 Console.WriteLine("Enter your first number ");
 int y = Convert.ToInt32(Console.ReadLine());

 Console.WriteLine("your vlaue of x is="+x+"\nyour value of y is="+y);

 int z = x;
 x = y;
 y = z;

 Console.WriteLine("after Swapping value of x is="+x+"/nyour value of y is="+y);
 Console.ReadLine();
}
</code></pre>

blocks|key|1355951|text|您可以尝试以下代码。它比其他代码要好得多。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1355952|a+=+a+%2B+b;
b+=+a+-+b;
a+=+a+-+b;|code-block|syntax|javascript|1355953|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|$]]

You can try the following code. It is much more better than the other code.

<pre><code>a = a + b;
b = a - b;
a = a - b;
</code></pre>

I'd like to be able to swap two variables without the use of a temporary variable in C#. Can this be done?

<pre><code>decimal startAngle = Convert.ToDecimal(159.9);
decimal stopAngle = Convert.ToDecimal(355.87);

// Swap each:
// startAngle becomes: 355.87
// stopAngle becomes: 159.9
</code></pre>

Swap two variables without using a temporary variable

我希望能够在C#中不使用临时变量的情况下交换两个变量。这可以做到吗？decimal startAngle = Convert.ToDecimal(159.9);decimal stopAngle = Convert.ToDecimal(355.87);// Swap each://   startAngle becomes: 355.87//   stopAngle becomes: 159.9

问交换两个变量而不使用临时变量
EN

回答 20

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问交换两个变量而不使用临时变量
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