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<pre>
<code style="font-family: Courier New, Courier, monospace; font-size: 12">
~/tcltk$<b> tclsh</b>
% <b>set Phrase "hello, world!"</b>
hello, world!
 
% <b>string toupper $Phrase</b>
HELLO, WORLD!
 
% <b>string totitle $Phrase</b>
Hello, world!
 
% <b>string match ello $Phrase</b>
0

% <b>string match *ello* $Phrase</b>
1

% <b>string length $Phrase</b>
14 

% <b>append Phrase "Nice day, eh?"</b>
hello, world!
Nice day, eh?

% <b>string toupper $Phrase</b>
HELLO, WORLD!
NICE DAY, EH? 

% <b>string wordend $Phrase 7</b>
12
			</code>
</pre>
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<td width="90%"><font size="4" face="Verdana, Arial, Helvetica"><b>Tcl strings and pattern matching</b></font></td><td width="200" align="right"><font size="1" face="Verdana, Arial, Helvetica"><nobr>   第 6 页（共15 页）</nobr></font></td>
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<p>Strings are the fundamental data type in Tcl. The 
				<i>string</i> command is really a variety of commands, 
				gathered under one umbrella. In use, <i>string</i> reads 
				much like the application of specific object methods from 
				OOP programming, as you can see in the example on the left.</p>
<p>The informational <i>string</i> commands are <i>length</i> and 
				<i>bytelength</i> (which can differ, depending on character set). 
				Comparisons that return boolean values (1 or 0) are <i>compare</i>, 
				<i>equal</i>, and <i>match</i>. Pattern matching here is accomplished 
				by "globbing", the simple type of matching commonly associated with 
				shell operations. Advanced Regular Expressions are also available 
				via the distinct regex and regsub commands.</p>
<p>Indexing functions in Tcl are performed with the 
				<i>index</i>, <i>last</i>, <i>first</i>, 
				<i>wordend</i>, and <i>wordstart</i> commands. String 
				modification is handled by <i>tolower</i>, <i>toupper</i>, 
				<i>totitle</i>, <i>trim</i>, <i>trimleft</i>, <i>trimright</i>, 
				<i>replace</i>, and <i>map</i>. The latter requires a character 
				mapping table to be pre-defined. Substrings are extracted with 
				<i>range</i>, and strings are output multiple times with 
				<i>repeat</i>.</p>
<p>Text can be added to an existing variable using the 
				<i>append</i> command. The <i>format</i> command can 
				be used to generate output strings using the same styles and 
				conventions as the C language's printf command. <i>scan</i> 
				parses a string and assigns values to variables. Finally, 
				starting with Tcl 8.0, functionality for handling binary data 
				as strings (thus able to process the null character without 
				failure) was added, with the <i>binary format</i> and <i>binary 
				scan</i> commands.</p>
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