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<h2 class="title"><a id="StringsTop"></a>Strings</h2>
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<p>
String variables are variables with a name starting with S or gS (for a local or global string variable, respectively). These variables can be used as input argument to any opcode that expects a quoted string constant, and can be manipulated at initialization or performance time with the opcodes listed below.
</p>
<p>
It is also possible to use string p-fields. The string p-field can be used by many orchestra opcodes
directly, or it can be copied to a string variable first:
</p>
<pre class="programlisting">
a1 <span class="opc">diskin2</span> p5, 1</pre>
<p>
</p>
<pre class="programlisting">
Sname <span class="opc">strget</span> p5
a1 <span class="opc">diskin2</span> Sname, 1</pre>
<p>
</p>
<p>
Strings within Csound can be expressed using traditional double
quotes (" "), and also using {{ }}. The second method is useful
to allow ';' and '$' characters within the string without having
to used ASCII codes.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<table border="0" summary="Note: Note">
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<td rowspan="2" align="center" valign="top" width="25">
<img alt="[Note]" src="images/note.png" />
</td>
<th align="left">Note</th>
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<tr>
<td align="left" valign="top">
<p>String variables and related opcodes are not available in Csound versions older than 5.00.</p>
</td>
</tr>
</table>
</div>
<p>
Strings can also be linked to a number using <a class="link" href="strset.html" title="strset"><em class="citetitle">strset</em></a> and <a class="link" href="strget.html" title="strget"><em class="citetitle">strget</em></a>.
</p>
<p>
Csound 5 also has improvements in parsing string constants. It is possible
to specify a multi-line string by enclosing it within {{ and }} instead of
the usual double quote characters, and the following escape sequences are
automatically converted:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p><span class="emphasis"><em>\a</em></span> alert bell</p>
</li>
<li class="listitem">
<p><span class="emphasis"><em>\b</em></span> backspace</p>
</li>
<li class="listitem">
<p><span class="emphasis"><em>\n</em></span> new line</p>
</li>
<li class="listitem">
<p><span class="emphasis"><em>\r</em></span> carriage return</p>
</li>
<li class="listitem">
<p><span class="emphasis"><em>\t</em></span> tab</p>
</li>
<li class="listitem">
<p><span class="emphasis"><em>\\</em></span> a single '\' character</p>
</li>
<li class="listitem">
<p><span class="emphasis"><em>\nnn</em></span> the character of which the ASCII code (in octal) is nnn</p>
</li>
</ul>
</div>
<p>
</p>
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<td align="left" valign="top">
<p>
If the user does not want an escaped sequence to be automatically converted, she has to escape it
with an additional '\' character so that Csound knows it does not have to interpret the escaped sequence.
For example the string <code class="code">"Not escaped\nline return"</code> will be converted to
</p>
<pre class="programlisting">
"Not escaped
line return"
</pre>
<p>
before being used, while the string <code class="code">"Escaped\\nline return"</code> will be converted to
</p>
<pre class="programlisting">
"Escaped\nline return"
</pre>
<p>
before being used.
</p>
</td>
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<p>
It can be useful together with the <a class="link" href="system.html" title="system"><em class="citetitle">system</em></a> opcode:
</p>
<pre class="programlisting">
<span class="oblock">instr</span> 1
<span class="comment">; csound5 lets you make a string with line returns inside double brackets</span>
<span class="opc">system</span> {{ ps
date
cd ~/Desktop
pwd
ls -l
whois csounds.com
}}
<span class="oblock">endin</span></pre>
<p>
And the <a class="link" href="py.html" title="Python Opcodes"><em class="citetitle">python opcodes</em></a>, among others:
</p>
<pre class="programlisting">
<span class="opc">pyruni</span> {{
import random
pool = [(1 + i/10.0) ** 1.2 for i in range(100)]
def get_number_from_pool(n, p):
if random.random() < p:
i = int(random.random() * len(pool))
pool[i] = n
return random.choice(pool)
}}</pre>
<p>
</p>
<div class="section">
<div class="titlepage">
<div>
<div>
<h2 class="title" style="clear: both"><a id="stringmanipulate"></a>String Manipulation Opcodes</h2>
</div>
</div>
</div>
<p>These opcodes perform operations on string variables (note: most of the opcodes run at init time only, and have a version with a "k" suffix that runs at both init and performance time; exceptions to this rule include puts and strget):</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a class="link" href="strcpy.html" title="strcpy"><em class="citetitle">strcpy</em></a> and <a class="link" href="strcpyk.html" title="strcpyk"><em class="citetitle">strcpyk</em></a> - Assigns to a string variable.</p>
</li>
<li class="listitem">
<p>
<a class="link" href="strcat.html" title="strcat"><em class="citetitle">strcat</em></a> and <a class="link" href="strcatk.html" title="strcatk"><em class="citetitle">strcatk</em></a> - Concatenates strings, and stores the result in a variable.</p>
</li>
<li class="listitem">
<p>
<a class="link" href="strcmp.html" title="strcmp"><em class="citetitle">strcmp</em></a> and <a class="link" href="strcmpk.html" title="strcmpk"><em class="citetitle">strcmpk</em></a> - Compares strings.</p>
</li>
<li class="listitem">
<p>
<a class="link" href="strget.html" title="strget"><em class="citetitle">strget</em></a> - Assigns to a string variable, from strset table at the specified index, or string score p-field.</p>
</li>
<li class="listitem">
<p>
<a class="link" href="strlen.html" title="strlen"><em class="citetitle">strlen</em></a> and <a class="link" href="strlenk.html" title="strlenk"><em class="citetitle">strlenk</em></a> - Returns the length of a string.</p>
</li>
<li class="listitem">
<p>
<a class="link" href="sprintf.html" title="sprintf"><em class="citetitle">sprintf</em></a> - printf-style formatted output conversion, storing the result in a string variable.</p>
</li>
<li class="listitem">
<p>
<a class="link" href="sprintfk.html" title="sprintfk"><em class="citetitle">sprintfk</em></a> - printf-style formatted output conversion, storing the result in a string variable at k-rate.</p>
</li>
<li class="listitem">
<p>
<a class="link" href="puts.html" title="puts"><em class="citetitle">puts</em></a> - Prints a string constant or variable.</p>
</li>
<li class="listitem">
<p>
<a class="link" href="strindex.html" title="strindex"><em class="citetitle">strindex</em></a> and <a class="link" href="strindexk.html" title="strindexk"><em class="citetitle">strindexk</em></a> - Returns the first occurence of a string in another string.</p>
</li>
<li class="listitem">
<p>
<a class="link" href="strrindex.html" title="strrindex"><em class="citetitle">strrindex</em></a> and <a class="link" href="strrindexk.html" title="strrindexk"><em class="citetitle">strrindexk</em></a> - Returns the last occurence of a string in another string.</p>
</li>
<li class="listitem">
<p>
<a class="link" href="strsub.html" title="strsub"><em class="citetitle">strsub</em></a> and <a class="link" href="strsubk.html" title="strsubk"><em class="citetitle">strsubk</em></a> - Returns a substring of the input string.</p>
</li>
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