help/info/octetstring.html

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  32 <h1>octetstring</h1>
  33 <hr align="left" width="75%">
  34 <p>The keyword <b><font face="Courier New">octetstring</font></b> denotes a basic string type whose distinguished values are the ordered sequences of&nbsp; 2n hexadecimal digits where n is a
  35 non-negative integer.</p>
  36 <ul>
  37   <li>octet string values are written between <a href="#double_quotation"> single quotes and followed by the capital letter O.</a> (' 'O).</li>
  38   <li>A octet string may be specified by its integer value using a <a href="#conversion">conversion function</a>.</li>
  39   <li>The <a href="#relation">relational operators</a> equality (==) and non-equality (!=) can be used to compare values of two octet strings</li>
  40   <li>The <a href="#shift">shift operators</a> perform the shift left (&lt;&lt;) and shift right (&gt;&gt;) operations.</li>
  41   <li>The <a href="#rotate">rotate operators</a> perform the rotate left (&lt;@) and rotate right (@&gt;) operations.</li>
  42   <li>The <a href="#concatenation"> concatenation operator</a> (&amp;) performs a simple concatenation from left to right.</li>
  43   <li>Bitwise operators (<a href="and4b.html">and4b</a>, <a href="not4b.html">not4b</a>, <a href="or4b.html">or4b</a>, <a href="xor4b.html"
  44     target="_blank">xor4b</a>) are used to manipulate bits in the string.</li>
  45   <li>A <a href="#array"> single octet</a> may be accessed using an array-like syntax. The leftmost octet has the index zero.</li>
  46   <li>The octet string may be <a href="#vacuum">empty</a>.</li>
  47   <li>The length of the octet string can be constrained using the keyword <a href="length.html"><b><font face="Courier New" color="#003258" size="4">length</font></b></a>.</li>
  48   <li>Another way to limit the permitted values of an octet string is <a href="#list">to list them</a>.</li>
  49   <li>Predefined functions operating on octet strings:</li>
  50   <ul>
  51     <li><a href="#bit2hex">oct2hex</a> converts an octet string value to a hexadecimal string.</li>
  52     <li><a href="#str2int">oct2int</a> converts an octet string to the equivalent integer.</li>
  53     <li><a href="#str2oct">oct2bit</a> converts an octet string to a binary string.</li>
  54     <li><a href="#bit2str">oct2str</a> displays an octet string as a character string.</li>
  55     <li><a href="#oct2unichar">oct2unichar</a> converts an octet string as an universal character string.</li>
  56     <li><a href="#unichar2oct">unichar2oct</a> converts an universal charcter string  to an octet string.</li>
  57     <li><a href="#lengthof">lengthof</a> returns an integer value indicating the number of octets in a string.</li>
  58     <li><a href="#get_stringencoding">get_stringencoding</a> identifies the encoding of an octet string.</li>
  59     <li><a href="#remove_bom">remove_bom</a> strips the BOM if it is present or returns the original octet string.</li>
  60   </ul>
  61 </ul>
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  65   <tr>
  66     <td width="100%">
  67     <p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<u>TITAN specific extension to the standard:</u></p>
  68     <ul>
  69       <ul>
  70         <li><a href="#oct2char">oct2char</a> converts an octet string to a character string.</li>
  71       </ul>
  72     </ul>
  73     </td>
  74   </tr>
  75 </table>
  76 </center>
  77 </div>
  78 <p>Related keywords:</p>
  79 <ul>
  80   <li><a href="bit2oct.html"><b><font face="Courier New" color="#003258" size="4">bit2oct</font></b></a></li>
  81   <li><a href="char2oct.html"><b><font face="Courier New" color="#003258" size="4">char2oct</font></b></a></li>
  82   <li><a href="hex2oct.html"><b><font face="Courier New" color="#003258" size="4">hex2oct</font></b></a></li>
  83   <li><a href="int2oct.html"><b><font face="Courier New" color="#003258" size="4">int2oct</font></b></a></li>
  84   <li><a href="length.html"><b><font face="Courier New" color="#003258" size="4">length</font></b></a></li>
  85   <li><a href="lengthof.html"><b><font face="Courier New" color="#003258" size="4">lengthof</font></b></a></li>
  86   <li><a href="oct2bit.html"><b><font face="Courier New" color="#003258" size="4">oct2bit</font></b></a></li>
  87   <li><a href="oct2char.html"><b><font face="Courier New" color="#003258" size="4">oct2char</font></b></a></li>
  88   <li><a href="oct2hex.html"><b><font face="Courier New" color="#003258" size="4">oct2hex</font></b></a></li>
  89   <li><a href="oct2int.html"><b><font face="Courier New" color="#003258" size="4">oct2int</font></b></a></li>
  90   <li><a href="oct2unichar.html"><b><font face="Courier New" color="#003258" size="4">oct2unichar</font></b></a></li>
  91   <li><a href="unichar2oct.html"><b><font face="Courier New" color="#003258" size="4">unichar2oct</font></b></a></li>
  92   <li><a href="oct2str.html"><b><font face="Courier New" color="#003258" size="4">oct2str</font></b></a></li>
  93   <li><a href="get_stringencoding.html"><b><font face="Courier New" color="#003258" size="4">get_stringencoding</font></b></a></li>
  94   <li><a href="remove_bom.html"><b><font face="Courier New" color="#003258" size="4">remove_bom</font></b></a></li>
  95   <li><a href="str2oct.html"><b><font face="Courier New" color="#003258" size="4">str2oct</font></b></a></li>
  96   <li><a href="substr.html"><b><font face="Courier New" color="#003258" size="4">substr</font></b></a></li>
  97   <li><a href="and4b.html"><b><font face="Courier New" color="#003258" size="4">and4bit</font></b></a></li>
  98   <li><a href="not4b.html"><b><font face="Courier New" color="#003258" size="4">not4bit</font></b></a></li>
  99   <li><a href="or4b.html"><b><font face="Courier New" color="#003258" size="4">or4bit</font></b></a></li>
 100   <li><a href="xor4b.html"><b><font face="Courier New" color="#003258" size="4">xor4bit</font></b></a></li>
 101 </ul>
 102 <hr align="left" width="50%">
 103 <div align="center">
 104 <center>
 105 <table border="0" width="90%" bgcolor="#FFB599" cellpadding="4">
 106   <tr>
 107     <td width="100%">
 108     <h3 align="center"><font face="Courier New" color="#003258" size="5"><b>octetstring</b></font></h3>
 109     </td>
 110   </tr>
 111 </table>
 112 </center>
 113 </div>
 114 <hr align="left" width="50%">
 115 <p><a name="double_quotation">Example 1</a>:
 116 <p><font face="Courier New">const octetstring c_ok := 'A5'O;<br>
 117 </font>
 118 <p>The constant defined is called c_ok and contains the octet string A5.</p>
 119 <hr align="left" width="50%">
 120 <p><a name="conversion">Example 2</a>:
 121 <p><font face="Courier New">const octetstring c_entier := int2oct (266,2);<br>
 122 </font>
 123 <p>The constant c_entier will contain the octet string 010A because the converted integer number (127 -&gt; 10A) must be coded on 2 octets and therefore padded with a leading zero.</p>
 124 <hr align="left" width="50%">
 125 <p><a name="relation">Example 3</a>:
 126 <p><font face="Courier New">const boolean c_niet := ( c_entier == c_ok );<br>
 127 </font>
 128 <p>The constant c_niet will have the value false, because two octet strings are not equal. The parentheses are optional.</p>
 129 <hr align="left" width="50%">
 130 <p><a name="concatenation">Example 4</a>:
 131 <p><font face="Courier New">const octetstring c_clotre := c_entier &amp; c_ok;<br>
 132 </font>
 133 <p>The constant c_clotre will contain the octet string 010AA5&nbsp;</p>
 134 <hr align="left" width="50%">
 135 <p><a name="array">Example 5</a>:
 136 <p><font face="Courier New">const octetstring c_samotny := c_entier[1];<br>
 137 </font>
 138 <p>The constant called c_samotny will contain the octet string 0A.</p>
 139 <hr align="left" width="50%">
 140 <p><a name="vacuum">Example 6</a>:
 141 <p><font face="Courier New">const octetstring c_nil := ''O;<br>
 142 </font>
 143 <p>The constant called c_nil will be an empty string.</p>
 144 <hr align="left" width="50%">
 145 <p><a name="bit2hex">Example 7a</a>:
 146 <p><font face="Courier New">const hexstring c_kungsen := oct2hex ('AA'O);</font><br>
 147 <p>The constant called c_kungsen will have the hexadecimal value AA. Although&nbsp;both values on the screen may look the same (AA), they have different types (octet string respective character
 148 string).</p>
 149 <hr align="left" width="50%">
 150 <p><a name="str2int">Example 7b</a>:
 151 <p><font face="Courier New">const integer c_prednost := oct2int ('55'O);<br>
 152 </font>
 153 <p>The constant called c_prednost will have the integer value 85. The result will be always positive.</p>
 154 <hr align="left" width="50%">
 155 <p><a name="str2oct">Example 7c</a>:
 156 <p><font face="Courier New">const bitstring c_kvar := oct2bit ('44'O);<br>
 157 </font>
 158 <p>The constant called c_kvar will contain the bit string 01000100.</p>
 159 <hr align="left" width="50%">
 160 <p><a name="bit2str">Example 7d</a>:
 161 <p><font face="Courier New">const charstring c_lettres := oct2str ('80FBBC0530A0'O);<br>
 162 </font>
 163 <p>The constant called c_lettres will contain the string 80FBBC0530A0 because the resulting character string has the double length as the octet string and contains only the characters '0' .. 'F'.</p>
 164 <hr align="left" width="50%">
 165 <p><a name="lengthof">Example 7e</a>:
 166 <p><font face="Courier New">const integer c_laenge := lengthof ('80FBBC0530A0'O);<br>
 167 </font>
 168 <p>The constant called c_laenge will have the value 6 corresponding to the number of octets in the string .</p>
 169 <hr align="left" width="50%">
 170 <p><a name="oct2char">Example 7f</a>:
 171 <p><font face="Courier New">const charstring c_specific := oct2char (’4469707379’O);<br>
 172 </font>
 173 <p>The constant called c_specific will contain the string &quot;Dipsy&quot; because the resulting character string will have the same length as the incoming octet string. The octets are
 174 interpreted as ISO/IEC 646 [8] codes (according to the IRV) and the resulting characters are stored in the returned string. Octet values higher than 7F cause an error.</p>
 175 <hr align="left" width="50%">
 176 <p><a name="list">Example 8</a>:
 177 <p><font face="Courier New">var octetstring c_hinder ('1010'O,'77'O,'AA55CC'O );<br>
 178 </font>
 179 <p>The variable called c_hinder may hold the octet strings 1010, 77 and AA55CC only.</p>
 180 <hr align="left" width="50%">
 181 <p><a name="rotate">Example 9</a>:&nbsp;</p>
 182 <p><font face="Courier New">const octetstring c_go_round := '1122334455'O &lt;@ (1+2);<br>
 183 </font>
 184 <p>The constant called c_go_round will hold the value '4455112233'O (the left operand rotated by three octets).</p>
 185 <hr align="left" width="50%">
 186 <p><a name="shift">Example 10</a>:</p>
 187 <p><font face="Courier New">const octetstring c_slip := '1122334455'O &lt;&lt; (1+1);<br>
 188 </font>
 189 <p>The constant called c_slip will hold the value '3344550000'O (the left operand shifted by two octets) .</p>
 190 <hr align="left" width="25%">
 191 <hr align="left" width="25%">
 192 <p align="left"><a HREF="BNF.html#bitstringkeyword">BNF definition</a> of <font face="Courier New">octetstring</font><br>
 193 <a HREF="BNF.html#bitstringvalue">BNF definition</a> of octetstring value</p>
 194 </body>
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