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<div class="chapter" title="Strings">
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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), and can store any string with a maximum length defined by the -+max_str_len command line flag (255 characters by default). These variables can be used as input argument to any opcode that exepcts 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 (" "), an also using {{ }}. The second method is useful to allow ';' and '$' characters within the string without having to used ASCII codes.
</p>
<div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;">
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<th align="left">Note</th>
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<td align="left" valign="top">
<p>String variables and related opcodes are not available in Csound versions older than 5.00.</p>
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<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 (note that the length of string constants is not limited, and is not affected by the -+max_str_len option), and the following escape sequences are automatically converted:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" 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>
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" title="String Manipulation Opcodes">
<div class="titlepage">
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<div>
<h2 class="title" style="clear: both"><a id="stringmanipulate"></a>String Manipulation Opcodes</h2>
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<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" 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>
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