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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE section PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<section id="str" xmlns:xi="http://www.w3.org/2001/XInclude">
<sectioninfo>
<revhistory>
<revision>
<revnumber>$Revision$</revnumber>
<date>$Date$</date>
</revision>
</revhistory>
</sectioninfo>
<title>Type <type>str</type></title>
<para>
One of our main goals was to make <acronym>SER</acronym> really
fast. There are many functions across the server that need to work with
strings. Usually these functions need to know string length. We wanted
to avoid using of <function>strlen</function> because the function is
relatively slow. It must scan the whole string and find the first
occurrence of zero character. To avoid this, we created
<type>str</type> type. The type has 2 fields, field
<structfield>s</structfield> is pointer to the beginning of the string
and field <structfield>len</structfield> is length of the string. We
then calculate length of the string only once and later reuse saved
value.
</para>
<important>
<para>
<type>str</type> structure is quite important because it is widely
used in <acronym>SER</acronym> (most functions accept
<type>str</type> instead of <type>char*</type>).
</para>
</important>
<para><emphasis><type>str</type> Type Declaration</emphasis></para>
<programlisting>
struct _str{
char* s;
int len;
};
typedef struct _str str;
</programlisting>
<para>
The declaration can be found in header file <filename>str.h</filename>.
</para>
<warning>
<para>
Because we store string lengths, there is no need to zero terminate
them. Some strings in the server are still zero terminated, some
are not. Be careful when using functions like
<function>snprintf</function> that rely on the ending zero. You can
print variable of type <type>str</type> this way:
<programlisting>
printf("%.*s", mystring->len, mystring->s);
</programlisting>
That ensures that the string will be printed correctly even if
there is no zero character at the end.
</para>
</warning>
</section>
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