C#中的换行符 | 码农家园

Line continue character in C#

我们有一个包含非常长字符串的变量的单元测试。

问题是如何在代码中编写它，而不会出现换行或代码难以读取的问题。

在vb中有一个行继续字符，在c中有等价物吗？

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C允许在多行上拆分一个字符串，该术语称为verbatim literal：

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string myString = @"this is a
test
to see how long my string
can be

and it can be quite long";

如果您正在寻找vb中的& _的替代方案，请使用+连接您的行。

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字符串恒量

只需使用+操作符，将字符串分解为人类可读的行。编译器会发现字符串是常量，并在编译时将它们连接起来。请参阅此处的msdn c编程指南。

例如

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const string myVeryLongString =
"This is the opening paragraph of my long string." +
"Which is split over multiple lines to improve code readability," +
"but is in fact, just one long string.";

IL_0003: ldstr "This is the opening paragraph of my long string. Which is split over multiple lines to improve code readability, but is in fact, just one long string."

字符串变量

注意，当使用字符串插值将值替换到字符串中时，需要在需要进行替换的每一行之前使用$字符：

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var interpolatedString =
"This line has no substitutions." +
$" This line uses {count} widgets, and" +
$" {CountFoos()} foos were found.";

但是，这会导致对string.Format的多次调用以及字符串的最终连接(用***标记)的负面性能后果。

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IL_002E: ldstr "This line has no substitutions."
IL_0033: ldstr " This line uses {0} widgets, and"
IL_0038: ldloc.0 // count
IL_0039: box System.Int32
IL_003E: call System.String.Format ***
IL_0043: ldstr " {0} foos were found."
IL_0048: ldloc.1 // CountFoos
IL_0049: callvirt System.Func<System.Int32>.Invoke
IL_004E: box System.Int32
IL_0053: call System.String.Format ***
IL_0058: call System.String.Concat ***

虽然您可以使用$@提供单个字符串并避免性能问题，但除非空白放在{}中(这看起来很奇怪，imo)，否则这与neil knight的答案有相同的问题，因为它将在行细分中包含任何空白：

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var interpolatedString = $@"When breaking up strings with `@` it introduces
<- [newLine and whitespace here!] each time I break the string.
<- [More whitespace] {CountFoos()} foos were found.";

注入的空白很容易被发现：

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IL_002E: ldstr "When breaking up strings with `@` it introduces
<- [newLine and whitespace here!] each time I break the string.
<- [More whitespace] {0} foos were found."

另一种选择是恢复到string.Format。这里，根据我的初始答案，格式化字符串是一个常量：

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const string longFormatString =
"This is the opening paragraph of my long string with {0} chars." +
"Which is split over multiple lines to improve code readability," +
"but is in fact, just one long string with {1} widgets.";

然后评估如下：

1	string.Format(longFormatString, longFormatString.Length, CountWidgets());

但是，考虑到格式化字符串和替换标记之间可能存在分离，这仍然很难维护。

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1 2	@"string here that is long you mean"

但是要小心，因为

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@"string here
and space before this text
means the space is also a part of the string"

它也会避开字符串中的内容

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@"c:\\folder" // c:\\folder
@"c:\folder" // c:\folder
"c:\\folder" // c:\folder

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如果声明了不同的变量，则使用以下简单方法：

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Int salary=2000;

String abc="I Love Pakistan";

Double pi=3.14;

Console.Writeline=salary+"/n"+abc+"/n"+pi;
Console.readkey();