<html><head><metahttp-equiv="X-UA-Compatible"content="IE=edge"/><linkrel="shortcut icon"href="../icons/favicon.ico"/><linkrel="stylesheet"type="text/css"href="../styles/branding.css"/><linkrel="stylesheet"type="text/css"href="../styles/branding-en-US.css"/><scripttype="text/javascript"src="../scripts/branding.js"></script><metahttp-equiv="Content-Type"content="text/html; charset=UTF-8"/><title>gmp_lib.mpz_init2 Method </title><metaname="Language"content="en-us"/><metaname="System.Keywords"content="mpz_init2 method"/><metaname="System.Keywords"content="gmp_lib.mpz_init2 method"/><metaname="Microsoft.Help.F1"content="Math.Gmp.Native.gmp_lib.mpz_init2"/><metaname="Microsoft.Help.Id"content="M:Math.Gmp.Native.gmp_lib.mpz_init2(Math.Gmp.Native.mpz_t,Math.Gmp.Native.mp_bitcnt_t)"/><metaname="Description"content="Initialize , with space for -bit numbers, and set its value to 0."/><metaname="Microsoft.Help.ContentType"content="Reference"/><metaname="BrandingAware"content="true"/><metaname="container"content="Math.Gmp.Native"/><metaname="file"content="5cd3a242-93b7-49c5-b9c9-1dca02ed4662"/><metaname="guid"content="5cd3a242-93b7-49c5-b9c9-1dca02ed4662"/><linktype="text/css"rel="stylesheet"href="../styles/highlight.css"/><scripttype="text/javascript"src="../scripts/highlight.js"></script><linkrel="stylesheet"type="text/css"href="../styles/branding-Website.css"/><scripttype="text/javascript"src="../scripts/jquery-1.11.0.min.js"></script><scripttype="text/javascript"src="../scripts/branding-Website.js"></script><scripttype="text/javascript"src="../scripts/clipboard.min.js"></script></head><bodyonload="OnLoad('cs')"><inputtype="hidden"id="userDataCache"class="userDataStyle"/><divclass="pageHeader"id="PageHeader">GMP Native Interface for .NET<formid="SearchForm"method="get"action="#"onsubmit="javascript:TransferToSearchPage(); return false;"><inputid="SearchTextBox"type="text"maxlength="200"/><buttonid="SearchButton"type="submit"></button></form></div><divclass="pageBody"><divclass="leftNav"id="leftNav"><divid="tocNav"><divclass="toclevel0"data-toclevel="0"><aclass="tocCollapsed"onclick="javascript: Toggle(this);"href="#!"/><adata-tochassubtree="true"href="846f5c8a-6cba-433e-9f18-cde2ff5695cd.htm"title="GMP Native Interface for .NET"tocid="roottoc">GMP Native Interface for .NET</a></div><divclass="toclevel0"data-toclevel="0"><aclass="tocCollapsed"onclick="javascript: Toggle(this);"href="#!"/><adata-tochassubtree="true"href="d9c51b9f-0c54-770b-28ea-6eebd8fef368.htm"title="Math.Gmp.Native"tocid="d9c51b9f-0c54-770b-28ea-6eebd8fef368">Math.Gmp.Native</a></div><divclass="toclevel0"data-toclevel="0"><aclass="tocCollapsed"onclick="javascript: Toggle(this);"href="#!"/><adata-tochassubtree="true"href="3af6b34c-3242-2b75-e7c7-ab79af8a4b0f.htm"title="gmp_lib Class"tocid="3af6b34c-3242-2b75-e7c7-ab79af8a4b0f">gmp_lib Class</a></div><divclass="toclevel1"data-toclevel="1"data-childrenloaded="true"><aclass="tocExpanded"onclick="javascript: Toggle(this);"href="#!"/><adata-tochassubtree="true"href="0fa7cbf3-e8f4-6b14-d829-8aa663e77c74.htm"title="gmp_lib Methods"tocid="0fa7cbf3-e8f4-6b14-d829-8aa663e77c74">gmp_lib Methods</a></div><divclass="toclevel2"data-toclevel="2"><adata-tochassubtree="false"href="c9cb6a67-59b8-5c03-f31d-f252441c53f6.htm"title="_mpz_realloc Method "tocid="c9cb6a67-59b8-5c03-f31d-f252441c53f6">_mpz_realloc Method </a></div><divclass="toclevel2"data-toclevel="2"><adata-tochassubtree="false"href="2c68671c-cd5c-e2ec-52a2-65b0ca31c3d1.htm"title="allocate Method "tocid="2c68671c-cd5c-e2ec-52a2-65b0ca31c3d1">allocate Method </a></div><divclass="toclevel2"data-toclevel="2"><aclass="tocCollapsed"onclick="javascript: Toggle(this);"href="#!"/><adata-tochassubtree="true"href="92160da3-b1af-e005-cb05-e3fb4dd524d8.htm"title="free Method "tocid="92160da3-b1af-e005-cb05-e3fb4dd524d8">free Method </a></div><divclass="toclevel2"data-toclevel="2"><adata-tochassubtree="false"href="fe6e46c3-84
Initialize <spanclass="parameter">x</span>, with space for <spanclass="parameter">n</span>-bit numbers, and set its value to <spanclass="code">0</span>.
</pre></div></div></div><scripttype="text/javascript">AddLanguageTabSet("ID0EDCA");</script><h4class="subHeading">Parameters</h4><dl><dt><spanclass="parameter">x</span></dt><dd>Type:<ahref="8beda7fb-bbc4-b56f-fd1f-1459377ecb3b.htm">Math.Gmp.Native<spanid="LST65E8C031_1"></span><scripttype="text/javascript">AddLanguageSpecificTextSet("LST65E8C031_1?cs=.|vb=.|cpp=::|nu=.|fs=.");</script>mpz_t</a><br/>The integer.</dd><dt><spanclass="parameter">n</span></dt><dd>Type:<ahref="1b2b1d64-20c1-7a64-0278-d9ff58ee9cc3.htm">Math.Gmp.Native<spanid="LST65E8C031_2"></span><scripttype="text/javascript">AddLanguageSpecificTextSet("LST65E8C031_2?cs=.|vb=.|cpp=::|nu=.|fs=.");</script>mp_bitcnt_t</a><br/>The number of bits.</dd></dl></div><divclass="collapsibleAreaRegion"><spanclass="collapsibleRegionTitle"onclick="SectionExpandCollapse('ID2RB')"onkeypress="SectionExpandCollapse_CheckKey('ID2RB', event)"tabindex="0"><imgid="ID2RBToggle"class="collapseToggle"src="../icons/SectionExpanded.png"/>Remarks</span></div><divid="ID2RBSection"class="collapsibleSection"><p>
Calling this function instead of <ahref="dc2f13ec-ac21-1196-0a1d-c574578b1f24.htm">mpz_init(mpz_t)</a> or <ahref="de0b7cf7-1826-55f3-379d-41a6ef2d0991.htm">mpz_inits(<spanid="LST65E8C031_3"></span><scripttype="text/javascript">AddLanguageSpecificTextSet("LST65E8C031_3?cpp=array<");</script>mpz_t<spanid="LST65E8C031_4"></span><scripttype="text/javascript">AddLanguageSpecificTextSet("LST65E8C031_4?cpp=>|cs=[]|vb=()|nu=[]|fs=[]");</script>)</a>
is never necessary; reallocation is handled automatically by GMP when needed.
</p><p>
While <spanclass="parameter">n</span> defines the initial space, <spanclass="parameter">x</span> will grow automatically in the normal way,
if necessary, for subsequent values stored.
<spanclass="selflink">mpz_init2(mpz_t, mp_bitcnt_t)</span> makes it possible to avoid such reallocations if a maximum size is known in advance.
</p><p>
In preparation for an operation, GMP often allocates one limb more than ultimately needed.
To make sure GMP will not perform reallocation for <spanclass="parameter">x</span>, you need to add the number of bits
in <ahref="bf1f694d-f9b2-6413-12e5-ebae603d5b49.htm">mp_limb_t</a> to <spanclass="parameter">n</span>.
</p></div><divclass="collapsibleAreaRegion"><spanclass="collapsibleRegionTitle"onclick="SectionExpandCollapse('ID3RB')"onkeypress="SectionExpandCollapse_CheckKey('ID3RB', event)"tabindex="0"><imgid="ID3RBToggle"class="collapseToggle"src="../icons/SectionExpanded.png"/>Examples</span></div><divid="ID3RBSection"class="collapsibleSection"><divclass="codeSnippetContainer"><divclass="codeSnippetContainerTabs"><divid="ID0EDAABA_tab1"class="codeSnippetContainerTab"><ahref="#"onclick="javascript:ChangeTab('ID0EDAABA','cs','1','4');return false;">C#</a></div><divid="ID0EDAABA_tab2"class="codeSnippetContainerTab"><ahref="#"onclick="javascript:ChangeTab('ID0EDAABA','vb','2','4');return false;">VB</a></div><divid="ID0EDAABA_tab3"class="codeSnippetContainerTabPhantom"><ahref="#"onclick="javascript:ChangeTab('ID0EDAABA','cpp','3','4');return false;">C++</a></div><divid="ID0EDAABA_tab4"class="codeSnippetContainerTabPhantom"><ahref="#"onclick="javascript:ChangeTab('ID0EDAABA','fs','4','4');return false;">F#</a></div></div><divclass="codeSnippetContainerCodeContainer"><divclass="codeSnippetToolBar"><divclass="codeSnippetToolBarText"><aid="ID0EDAABA_copyCode"href="#"class="copyCodeSnippet"onclick="javascript:CopyToClipboard('ID0EDAABA');return false;"title="Copy">Copy</a></div></div><divid="ID0EDAABA_code_Div1"class="codeSnippetContainerCode"style="display: block"><prexml:space="preserve"><spanclass="highlight-comment">// Create a new integer x, and initialize its size to 300 bits.</span>
mpz_t x = <spanclass="highlight-keyword">new</span> mpz_t();
<spanclass="highlight-comment">// Release unmanaged memory allocated for x.</span>
gmp_lib.mpz_clear(x);</pre></div><divid="ID0EDAABA_code_Div2"class="codeSnippetContainerCode"style="display: none"><prexml:space="preserve"><spanclass="highlight-comment">' Create a new integer x, and initialize its size to 300 bits.</span>
<spanclass="highlight-keyword">Dim</span> x <spanclass="highlight-keyword">As</span><spanclass="highlight-keyword">New</span> mpz_t()
<spanclass="highlight-comment">' Release unmanaged memory allocated for x.</span>
gmp_lib.mpz_clear(x)</pre></div><divid="ID0EDAABA_code_Div3"class="codeSnippetContainerCode"style="display: none"><p>No code example is currently available or this language may not be supported.</p></div><divid="ID0EDAABA_code_Div4"class="codeSnippetContainerCode"style="display: none"><p>No code example is currently available or this language may not be supported.</p></div></div></div><scripttype="text/javascript">AddLanguageTabSet("ID0EDAABA");</script></div><divclass="collapsibleAreaRegion"id="seeAlsoSection"><spanclass="collapsibleRegionTitle"onclick="SectionExpandCollapse('ID4RB')"onkeypress="SectionExpandCollapse_CheckKey('ID4RB', event)"tabindex="0"><imgid="ID4RBToggle"class="collapseToggle"src="../icons/SectionExpanded.png"/>See Also</span></div><divid="ID4RBSection"class="collapsibleSection"><h4class="subHeading">Reference</h4><divclass="seeAlsoStyle"><ahref="3af6b34c-3242-2b75-e7c7-ab79af8a4b0f.htm">gmp_lib Class</a></div><divclass="seeAlsoStyle"><ahref="d9c51b9f-0c54-770b-28ea-6eebd8fef368.htm">Math.Gmp.Native Namespace</a></div><divclass="seeAlsoStyle"><ahref="551f8670-3080-9a92-cd50-58d09cbf77ef.htm">gmp_lib<spanid="LST65E8C031_5"></span><scripttype="text/javascript">AddLanguageSpecificTextSet("LST65E8C031_5?cs=.|vb=.|cpp=::|nu=.|fs=.");</script>mpz_clear(mpz_t)</a></div><divclass="seeAlsoStyle"><ahref="a909faa8-4939-1ba3-5647-af8836c9a291.htm">gmp_lib<spanid="LST65E8C031_6"></span><scripttype="text/javascript">AddLanguageSpecificTextSet("LST65E8C031_6?cs=.|vb=.|cpp=::|nu=.|fs=.");</script>mpz_clears(<spanid="LST65E8C031_7"></span><scripttype="text/javascript">AddLanguageSpecificTextSet("LST65E8C031_7?cpp=array<");</script>mpz_t<spanid="LST65E8C031_8"></span><scripttype="text/javascript">AddLanguageSpecificTextSet("LST65E8C031_8?cpp=>|cs=[]|vb=()|nu=[]|fs=[]");</script>)</a></div><divclass="seeAlsoStyle"><ahref="dc2f13ec-ac21-1196-0a1d-c574578b1f24.htm">gmp_lib<spanid="LST65E8C031_9"></span><scripttype="text/javascript">AddLanguageSpecificTextSet("LST65E8C031_9?cs=.|vb=.|cpp=::|nu=.|fs=.");</script>mpz_init(mpz_t)</a></div><divclass="seeAlsoStyle"><ahref="de0b7cf7-1826-55f3-379d-41a6ef2d0991.htm">gmp_lib<spanid="LST65E8C031_10"></span><scripttype="text/javascript">AddLanguageSpecificTextSet("LST65E8C031_10?cs=.|vb=.|cpp=::|nu=.|fs=.");</script>mpz_inits(<spanid="LST65E8C031_11"></span><scripttype="text/javascript">AddLanguageSpecificTextSet("LST65E8C031_11?cpp=array<");</script>mpz_t<spanid="LST65E8C031_12"></span><scripttype="text/javascript">AddLanguageSpecificTextSet("LST65E8C031_12?cpp=>|cs=[]|vb=()|nu=[]|fs=[]");</script>)</a></div><divclass="seeAlsoStyle"><ahref="1de9b70a-1d21-8168-e41c-1c259f64091a.htm">gmp_lib<spanid="LST65E8C031_13"></span><scripttype="text/javascript">AddLanguageSpecificTextSet("LST65E8C031_13?cs=.|vb=.|cpp=::|nu=.|fs=.");</script>mpz_realloc2(mpz_t, mp_bitcnt_t)</a></div><divclass="seeAlsoStyle"><ahref="3af6b34c-3242-2b75-e7c7-ab79af8a4b0f.htm"><ahref="https://gmplib.org/manual/Initializing-Integers.html#Initializing-Integers">GNU MP - Initializing Integers</a></a></div></div></div></div><divid="pageFooter"class="pageFooter"></div></body></html>