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1<?xml version="1.0" encoding="UTF-8" standalone="no"?>2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>9.6. Bit String Functions and Operators</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="functions-binarystring.html" title="9.5. Binary String Functions and Operators" /><link rel="next" href="functions-matching.html" title="9.7. Pattern Matching" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">9.6. Bit String Functions and Operators</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="functions-binarystring.html" title="9.5. Binary String Functions and Operators">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="functions.html" title="Chapter 9. Functions and Operators">Up</a></td><th width="60%" align="center">Chapter 9. Functions and Operators</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 16.3 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="functions-matching.html" title="9.7. Pattern Matching">Next</a></td></tr></table><hr /></div><div class="sect1" id="FUNCTIONS-BITSTRING"><div class="titlepage"><div><div><h2 class="title" style="clear: both">9.6. Bit String Functions and Operators <a href="#FUNCTIONS-BITSTRING" class="id_link">#</a></h2></div></div></div><a id="id-1.5.8.12.2" class="indexterm"></a><p>3 This section describes functions and operators for examining and4 manipulating bit strings, that is values of the types5 <code class="type">bit</code> and <code class="type">bit varying</code>. (While only6 type <code class="type">bit</code> is mentioned in these tables, values of7 type <code class="type">bit varying</code> can be used interchangeably.)8 Bit strings support the usual comparison operators shown in9 <a class="xref" href="functions-comparison.html#FUNCTIONS-COMPARISON-OP-TABLE" title="Table 9.1. Comparison Operators">Table 9.1</a>, as well as the10 operators shown in <a class="xref" href="functions-bitstring.html#FUNCTIONS-BIT-STRING-OP-TABLE" title="Table 9.14. Bit String Operators">Table 9.14</a>.11 </p><div class="table" id="FUNCTIONS-BIT-STRING-OP-TABLE"><p class="title"><strong>Table 9.14. Bit String Operators</strong></p><div class="table-contents"><table class="table" summary="Bit String Operators" border="1"><colgroup><col /></colgroup><thead><tr><th class="func_table_entry"><p class="func_signature">12 Operator13 </p>14 <p>15 Description16 </p>17 <p>18 Example(s)19 </p></th></tr></thead><tbody><tr><td class="func_table_entry"><p class="func_signature">20 <code class="type">bit</code> <code class="literal">||</code> <code class="type">bit</code>21 → <code class="returnvalue">bit</code>22 </p>23 <p>24 Concatenation25 </p>26 <p>27 <code class="literal">B'10001' || B'011'</code>28 → <code class="returnvalue">10001011</code>29 </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">30 <code class="type">bit</code> <code class="literal">&</code> <code class="type">bit</code>31 → <code class="returnvalue">bit</code>32 </p>33 <p>34 Bitwise AND (inputs must be of equal length)35 </p>36 <p>37 <code class="literal">B'10001' & B'01101'</code>38 → <code class="returnvalue">00001</code>39 </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">40 <code class="type">bit</code> <code class="literal">|</code> <code class="type">bit</code>41 → <code class="returnvalue">bit</code>42 </p>43 <p>44 Bitwise OR (inputs must be of equal length)45 </p>46 <p>47 <code class="literal">B'10001' | B'01101'</code>48 → <code class="returnvalue">11101</code>49 </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">50 <code class="type">bit</code> <code class="literal">#</code> <code class="type">bit</code>51 → <code class="returnvalue">bit</code>52 </p>53 <p>54 Bitwise exclusive OR (inputs must be of equal length)55 </p>56 <p>57 <code class="literal">B'10001' # B'01101'</code>58 → <code class="returnvalue">11100</code>59 </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">60 <code class="literal">~</code> <code class="type">bit</code>61 → <code class="returnvalue">bit</code>62 </p>63 <p>64 Bitwise NOT65 </p>66 <p>67 <code class="literal">~ B'10001'</code>68 → <code class="returnvalue">01110</code>69 </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">70 <code class="type">bit</code> <code class="literal"><<</code> <code class="type">integer</code>71 → <code class="returnvalue">bit</code>72 </p>73 <p>74 Bitwise shift left75 (string length is preserved)76 </p>77 <p>78 <code class="literal">B'10001' << 3</code>79 → <code class="returnvalue">01000</code>80 </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">81 <code class="type">bit</code> <code class="literal">>></code> <code class="type">integer</code>82 → <code class="returnvalue">bit</code>83 </p>84 <p>85 Bitwise shift right86 (string length is preserved)87 </p>88 <p>89 <code class="literal">B'10001' >> 2</code>90 → <code class="returnvalue">00100</code>91 </p></td></tr></tbody></table></div></div><br class="table-break" /><p>92 Some of the functions available for binary strings are also available93 for bit strings, as shown in <a class="xref" href="functions-bitstring.html#FUNCTIONS-BIT-STRING-TABLE" title="Table 9.15. Bit String Functions">Table 9.15</a>.94 </p><div class="table" id="FUNCTIONS-BIT-STRING-TABLE"><p class="title"><strong>Table 9.15. Bit String Functions</strong></p><div class="table-contents"><table class="table" summary="Bit String Functions" border="1"><colgroup><col /></colgroup><thead><tr><th class="func_table_entry"><p class="func_signature">95 Function96 </p>97 <p>98 Description99 </p>100 <p>101 Example(s)102 </p></th></tr></thead><tbody><tr><td class="func_table_entry"><p class="func_signature">103 <a id="id-1.5.8.12.6.2.2.1.1.1.1" class="indexterm"></a>104 <code class="function">bit_count</code> ( <code class="type">bit</code> )105 → <code class="returnvalue">bigint</code>106 </p>107 <p>108 Returns the number of bits set in the bit string (also known as109 <span class="quote">“<span class="quote">popcount</span>”</span>).110 </p>111 <p>112 <code class="literal">bit_count(B'10111')</code>113 → <code class="returnvalue">4</code>114 </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">115 <a id="id-1.5.8.12.6.2.2.2.1.1.1" class="indexterm"></a>116 <code class="function">bit_length</code> ( <code class="type">bit</code> )117 → <code class="returnvalue">integer</code>118 </p>119 <p>120 Returns number of bits in the bit string.121 </p>122 <p>123 <code class="literal">bit_length(B'10111')</code>124 → <code class="returnvalue">5</code>125 </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">126 <a id="id-1.5.8.12.6.2.2.3.1.1.1" class="indexterm"></a>127 <a id="id-1.5.8.12.6.2.2.3.1.1.2" class="indexterm"></a>128 <code class="function">length</code> ( <code class="type">bit</code> )129 → <code class="returnvalue">integer</code>130 </p>131 <p>132 Returns number of bits in the bit string.133 </p>134 <p>135 <code class="literal">length(B'10111')</code>136 → <code class="returnvalue">5</code>137 </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">138 <a id="id-1.5.8.12.6.2.2.4.1.1.1" class="indexterm"></a>139 <code class="function">octet_length</code> ( <code class="type">bit</code> )140 → <code class="returnvalue">integer</code>141 </p>142 <p>143 Returns number of bytes in the bit string.144 </p>145 <p>146 <code class="literal">octet_length(B'1011111011')</code>147 → <code class="returnvalue">2</code>148 </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">149 <a id="id-1.5.8.12.6.2.2.5.1.1.1" class="indexterm"></a>150 <code class="function">overlay</code> ( <em class="parameter"><code>bits</code></em> <code class="type">bit</code> <code class="literal">PLACING</code> <em class="parameter"><code>newsubstring</code></em> <code class="type">bit</code> <code class="literal">FROM</code> <em class="parameter"><code>start</code></em> <code class="type">integer</code> [<span class="optional"> <code class="literal">FOR</code> <em class="parameter"><code>count</code></em> <code class="type">integer</code> </span>] )151 → <code class="returnvalue">bit</code>152 </p>153 <p>154 Replaces the substring of <em class="parameter"><code>bits</code></em> that starts at155 the <em class="parameter"><code>start</code></em>'th bit and extends156 for <em class="parameter"><code>count</code></em> bits157 with <em class="parameter"><code>newsubstring</code></em>.158 If <em class="parameter"><code>count</code></em> is omitted, it defaults to the length159 of <em class="parameter"><code>newsubstring</code></em>.160 </p>161 <p>162 <code class="literal">overlay(B'01010101010101010' placing B'11111' from 2 for 3)</code>163 → <code class="returnvalue">0111110101010101010</code>164 </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">165 <a id="id-1.5.8.12.6.2.2.6.1.1.1" class="indexterm"></a>166 <code class="function">position</code> ( <em class="parameter"><code>substring</code></em> <code class="type">bit</code> <code class="literal">IN</code> <em class="parameter"><code>bits</code></em> <code class="type">bit</code> )167 → <code class="returnvalue">integer</code>168 </p>169 <p>170 Returns first starting index of the specified <em class="parameter"><code>substring</code></em>171 within <em class="parameter"><code>bits</code></em>, or zero if it's not present.172 </p>173 <p>174 <code class="literal">position(B'010' in B'000001101011')</code>175 → <code class="returnvalue">8</code>176 </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">177 <a id="id-1.5.8.12.6.2.2.7.1.1.1" class="indexterm"></a>178 <code class="function">substring</code> ( <em class="parameter"><code>bits</code></em> <code class="type">bit</code> [<span class="optional"> <code class="literal">FROM</code> <em class="parameter"><code>start</code></em> <code class="type">integer</code> </span>] [<span class="optional"> <code class="literal">FOR</code> <em class="parameter"><code>count</code></em> <code class="type">integer</code> </span>] )179 → <code class="returnvalue">bit</code>180 </p>181 <p>182 Extracts the substring of <em class="parameter"><code>bits</code></em> starting at183 the <em class="parameter"><code>start</code></em>'th bit if that is specified,184 and stopping after <em class="parameter"><code>count</code></em> bits if that is185 specified. Provide at least one of <em class="parameter"><code>start</code></em>186 and <em class="parameter"><code>count</code></em>.187 </p>188 <p>189 <code class="literal">substring(B'110010111111' from 3 for 2)</code>190 → <code class="returnvalue">00</code>191 </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">192 <a id="id-1.5.8.12.6.2.2.8.1.1.1" class="indexterm"></a>193 <code class="function">get_bit</code> ( <em class="parameter"><code>bits</code></em> <code class="type">bit</code>,194 <em class="parameter"><code>n</code></em> <code class="type">integer</code> )195 → <code class="returnvalue">integer</code>196 </p>197 <p>198 Extracts <em class="parameter"><code>n</code></em>'th bit199 from bit string; the first (leftmost) bit is bit 0.200 </p>201 <p>202 <code class="literal">get_bit(B'101010101010101010', 6)</code>203 → <code class="returnvalue">1</code>204 </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">205 <a id="id-1.5.8.12.6.2.2.9.1.1.1" class="indexterm"></a>206 <code class="function">set_bit</code> ( <em class="parameter"><code>bits</code></em> <code class="type">bit</code>,207 <em class="parameter"><code>n</code></em> <code class="type">integer</code>,208 <em class="parameter"><code>newvalue</code></em> <code class="type">integer</code> )209 → <code class="returnvalue">bit</code>210 </p>211 <p>212 Sets <em class="parameter"><code>n</code></em>'th bit in213 bit string to <em class="parameter"><code>newvalue</code></em>;214 the first (leftmost) bit is bit 0.215 </p>216 <p>217 <code class="literal">set_bit(B'101010101010101010', 6, 0)</code>218 → <code class="returnvalue">101010001010101010</code>219 </p></td></tr></tbody></table></div></div><br class="table-break" /><p>220 In addition, it is possible to cast integral values to and from type221 <code class="type">bit</code>.222 Casting an integer to <code class="type">bit(n)</code> copies the rightmost223 <code class="literal">n</code> bits. Casting an integer to a bit string width wider224 than the integer itself will sign-extend on the left.225 Some examples:226</p><pre class="programlisting">22744::bit(10) <em class="lineannotation"><span class="lineannotation">0000101100</span></em>22844::bit(3) <em class="lineannotation"><span class="lineannotation">100</span></em>229cast(-44 as bit(12)) <em class="lineannotation"><span class="lineannotation">111111010100</span></em>230'1110'::bit(4)::integer <em class="lineannotation"><span class="lineannotation">14</span></em>231</pre><p>232 Note that casting to just <span class="quote">“<span class="quote">bit</span>”</span> means casting to233 <code class="literal">bit(1)</code>, and so will deliver only the least significant234 bit of the integer.235 </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="functions-binarystring.html" title="9.5. Binary String Functions and Operators">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="functions.html" title="Chapter 9. Functions and Operators">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="functions-matching.html" title="9.7. Pattern Matching">Next</a></td></tr><tr><td width="40%" align="left" valign="top">9.5. Binary String Functions and Operators </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 16.3 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 9.7. Pattern Matching</td></tr></table></div></body></html>