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<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8" /><title>Hyperlinked ECMA C# Language Specification</title><meta name="author" content="Jon Jagger" /><link rel="stylesheet" href="ecma334.css"></link></head><body><div align="right"><em><a href="http://www.jaggersoft.com">Jon Jagger</a></em></div><div align="right"><a href="mailto:jon@jaggersoft.com">jon@jaggersoft.com</a></div><form method="get" action="http://search.atomz.com/search/"><input size="30" name="sp-q"></input><input type="submit" value="Search C# Spec"></input><input type="hidden" name="sp-a" value="sp10024177"></input><input type="hidden" name="sp-f" value="ISO-8859-1"></input></form><a href="toc.htm">Table of Contents</a> <a href="1.htm">1</a> <a href="2.htm">2</a> <a href="3.htm">3</a> <a href="4.htm">4</a> <a href="5.htm">5</a> <a href="6.htm">6</a> <a href="7.htm">7</a> <a href="8.htm">8</a> <a href="9.htm">9</a> <a href="10.htm">10</a> <a href="11.htm">11</a> <a href="12.htm">12</a> <a href="13.htm">13</a> <a href="14.htm">14</a> <a href="15.htm">15</a> <a href="16.htm">16</a> <a href="17.htm">17</a> <a href="18.htm">18</a> <a href="19.htm">19</a> <a href="20.htm">20</a> <a href="21.htm">21</a> <a href="22.htm">22</a> <a href="23.htm">23</a> <a href="24.htm">24</a> <a href="25.htm">25</a> <a href="notes.htm">Notes</a> <a href="HyperlinkedCSharpECMA.zip">Download</a><span class="ruler"></span><span class="heading">ECMA-334 C# Language Specification</span><span class="navigate"><a href="9.4.4.4.htm"><img src="previous.gif" alt="previous" border="0" /></a><a href="9.4.4.6.htm"><img src="next.gif" alt="next" border="0" /></a></span><span class="clause-depth"><a href="8.htm"><img src="previous.gif" alt="previous at this level" border="0" /></a><a href="10.htm"><img src="next.gif" alt="next at this level" border="0" /></a> <span class="clause-number-link"><a href="9.htm">9</a></span><span class="clause-title-previous"> Lexical structure</span></span><span class="clause-depth"><a href="9.3.htm"><img src="previous.gif" alt="previous at this level" border="0" /></a><a href="9.5.htm"><img src="next.gif" alt="next at this level" border="0" /></a> <span class="clause-number-link"><a href="9.4.htm">9.4</a></span><span class="clause-title-previous"> Tokens</span></span><span class="clause-depth"><a href="9.4.3.htm"><img src="previous.gif" alt="previous at this level" border="0" /></a><a href="9.4.5.htm"><img src="next.gif" alt="next at this level" border="0" /></a> <span class="clause-number-link"><a href="9.4.4.htm">9.4.4</a></span><span class="clause-title-previous"> Literals</span></span><span class="clause-depth"><a href="9.4.4.4.htm"><img src="previous.gif" alt="previous at this level" border="0" /></a><a href="9.4.4.6.htm"><img src="next.gif" alt="next at this level" border="0" /></a> <span class="clause-number">9.4.4.5</span><span class="clause-title"> String literals</span></span><span class="sentence"><span class="sentence-number">1</span> <a name="P0S1"></a>C# supports two forms of string literals: regular string literals and verbatim string literals.</span> <span class="sentence"><span class="sentence-number">2</span> <a name="P0S2"></a>A regular string literal consists of zero or more characters enclosed in <span class="keyword">double</span> quotes, as in "hello, world", and may include both simple escape sequences (such as \t for the tab character), and hexadecimal and Unicode escape sequences.</span> <span class="locator">
Paragraph 1</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P1S1"></a>A verbatim string literal consists of an @ character followed by a double-quote character, zero or more </span></span><span class="paragraph"><span class="sentence"><span class="sentence-number">2</span> <a name="P1S2"></a>characters, and a closing double-quote character.</span> <span class="example">[Example: A simple example is @"hello, world". end example]</span> <span class="sentence"><span class="sentence-number">3</span> <a name="P1S3"></a>In a verbatim string literal, the characters between the delimiters are interpreted verbatim, with the only exception being a <span class="non-terminal"><a href="9.4.4.5.htm#quote-escape-sequence">quote-escape-sequence</a></span>.</span> <span class="sentence"><span class="sentence-number">4</span> <a name="P1S4"></a>In particular, simple escape sequences, and hexadecimal and Unicode escape sequences are not processed in verbatim string literals.</span> <span class="sentence"><span class="sentence-number">5</span> <a name="P1S5"></a>A verbatim string literal may span multiple lines.</span> <span class="grammar-production"><span class="name"><a name="string-literal"></a>string-literal</span> :: <span class="rhs"><span class="non-terminal"><a href="9.4.4.5.htm#regular-string-literal">regular-string-literal</a></span> </span><span class="rhs"><span class="non-terminal"><a href="9.4.4.5.htm#verbatim-string-literal">verbatim-string-literal</a></span> </span></span><span class="grammar-production"><span class="name"><a name="regular-string-literal"></a>regular-string-literal</span> :: <span class="rhs"><span class="terminal">"</span> <span class="non-terminal"><a href="9.4.4.5.htm#regular-string-literal-characters">regular-string-literal-characters</a></span><sub>opt</sub> <span class="terminal">"</span> </span></span><span class="grammar-production"><span class="name"><a name="regular-string-literal-characters"></a>regular-string-literal-characters</span> :: <span class="rhs"><span class="non-terminal"><a href="9.4.4.5.htm#regular-string-literal-character">regular-string-literal-character</a></span> </span><span class="rhs"><span class="non-terminal"><a href="9.4.4.5.htm#regular-string-literal-characters">regular-string-literal-characters</a></span> <span class="non-terminal"><a href="9.4.4.5.htm#regular-string-literal-character">regular-string-literal-character</a></span> </span></span><span class="grammar-production"><span class="name"><a name="regular-string-literal-character"></a>regular-string-literal-character</span> :: <span class="rhs"><span class="non-terminal"><a href="9.4.4.5.htm#single-regular-string-literal-character">single-regular-string-literal-character</a></span> </span><span class="rhs"><span class="non-terminal"><a href="9.4.4.4.htm#simple-escape-sequence">simple-escape-sequence</a></span> </span><span class="rhs"><span class="non-terminal"><a href="9.4.4.4.htm#hexadecimal-escape-sequence">hexadecimal-escape-sequence</a></span> </span><span class="rhs"><span class="non-terminal"><a href="9.4.1.htm#unicode-escape-sequence">unicode-escape-sequence</a></span> </span></span><span class="grammar-production"><span class="name"><a name="single-regular-string-literal-character"></a>single-regular-string-literal-character</span> :: <span class="rhs">Any character except " (U+0022), \ (U+005C), and <span class="non-terminal"><a href="9.3.2.htm#new-line-character">new-line-character</a></span> </span></span><span class="grammar-production"><span class="name"><a name="verbatim-string-literal"></a>verbatim-string-literal</span> :: <span class="rhs"><span class="terminal">@"</span> <span class="non-terminal"><a href="9.4.4.5.htm#verbatim-string-literal-characters">verbatim-string-literal-characters</a></span><sub>opt</sub> <span class="terminal">"</span> </span></span><span class="grammar-production"><span class="name"><a name="verbatim-string-literal-characters"></a>verbatim-string-literal-characters</span> :: <span class="rhs"><span class="non-terminal"><a href="9.4.4.5.htm#verbatim-string-literal-character">verbatim-string-literal-character</a></span> </span><span class="rhs"><span class="non-terminal"><a href="9.4.4.5.htm#verbatim-string-literal-characters">verbatim-string-literal-characters</a></span> <span class="non-terminal"><a href="9.4.4.5.htm#verbatim-string-literal-character">verbatim-string-literal-character</a></span> </span></span><span class="grammar-production"><span class="name"><a name="verbatim-string-literal-character"></a>verbatim-string-literal-character</span> :: <span class="rhs"><span class="non-terminal"><a href="9.4.4.5.htm#single-verbatim-string-literal-character">single-verbatim-string-literal-character</a></span> </span><span class="rhs"><span class="non-terminal"><a href="9.4.4.5.htm#quote-escape-sequence">quote-escape-sequence</a></span> </span></span><span class="grammar-production"><span class="name"><a name="single-verbatim-string-literal-character"></a>single-verbatim-string-literal-character</span> :: <span class="rhs">Any character except " </span></span><span class="grammar-production"><span class="name"><a name="quote-escape-sequence"></a>quote-escape-sequence</span> :: <span class="rhs"><span class="terminal">""</span> </span></span></span><span class="paragraph"><span class="note">[Note: A character that follows a backslash character (\) in a <span class="non-terminal"><a href="9.4.4.5.htm#regular-string-literal-character">regular-string-literal-character</a></span> must be one of the following characters: ', ", \, 0, a, b, f, n, r, t, u, U, x, v. Otherwise, a compile-time error occurs. end note]</span> </span><span class="paragraph"><span class="example">[Example: The example <pre class="code-example">
string a = "Happy birthday, Joel"; // Happy birthday, Joel
string b = @"Happy birthday, Joel"; // Happy birthday, Joel
string c = "hello \t world"; // hello world
string d = @"hello \t world"; // hello \t world
string e = "Joe said \"Hello\" to me"; // Joe said "Hello" to me
string f = @"Joe said ""Hello"" to me"; // Joe said "Hello" to me
string g = "\\\\server\\share\\file.txt"; // \\server\share\file.txt
string h = @"\\server\share\file.txt"; // \\server\share\file.txt
string i = "one\r\ntwo\r\nthree";
string j = @"one
two
three";
</pre>shows a variety of string literals. The last string literal, j, is a verbatim string literal that spans multiple lines. The characters between the quotation marks, including white space such as new line characters, are preserved verbatim. end example]</span> </span><span class="paragraph"><span class="note">[Note: Since a hexadecimal escape sequence can have a variable number of hex digits, the string literal "\x123" contains a single character with hex value 123. To create a string containing the character with hex value 12 followed by the character 3, one could write "\x00123" or "\x12" + "3" instead. end note]</span> </span><span class="locator">
Paragraph 2</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P2S1"></a>The type of a <span class="non-terminal"><a href="9.4.4.5.htm#string-literal">string-literal</a></span> is string.</span> </span><span class="locator">
Paragraph 3</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P3S1"></a>Each string literal does not necessarily result in a new string instance.</span> <span class="sentence"><span class="sentence-number">2</span> <a name="P3S2"></a>When two or more string literals that are equivalent according to the string equality operator (<a href="14.9.7.htm">§14.9.7</a>), appear in the same assembly, these string literals refer to the same string instance.</span> <span class="example">[Example: For instance, the output produced by <pre class="code-example">
class Test
{
static void Main() {
object a = "hello";
object b = "hello";
System.Console.WriteLine(a == b);
}
}
</pre>is True because the two literals refer to the same string instance. end example]</span> </span><span class="ruler"></span><table><tr><td><table align="left" bgcolor="navy"><tr bgcolor="navy"><td><font face="Arial,sans-serif" size="6" color="yellow"><strong>{ JSL }</strong></font></td></tr></table></td></tr><tr><td><font face="Arial,sans-serif" size="2" color="navy"><strong>Jagger Software Ltd</strong></font></td></tr><tr><td><font face="Arial,sans-serif" size="2" color="navy"><strong>Company # 4070126</strong></font></td></tr><tr><td><font face="Arial,sans-serif" size="2" color="navy"><strong>VAT # 762 5213 42</strong></font></td></tr></table><img src="valid-html401.png" align="left" height="31" width="88" alt="Valid HTML 4.01" /><img src="vcss.gif" align="left" height="31" width="88" alt="Valid CSS" /></body></html>⌨️ 快捷键说明
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