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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head> <meta name="generator" content= "HTML Tidy for Linux/x86 (vers 1 September 2005), see www.w3.org"> <title>new</title> <link href="../cppreference.css" rel="stylesheet" type="text/css"></head><body><table> <tr> <td> <div class="body-content"> <div class="header-box"> <a href="../index.html">cppreference.com</a> > <a href= "index.html">C/C++ Keywords</a> > <a href="new.html">new</a> </div> <div class="name-format"> new </div> <div class="syntax-name-format"> Syntax: </div> <pre class="syntax-box"> pointer = new type; pointer = new type( initializer ); pointer = new type[size]; pointer = new( arg-list ) type...</pre> <p>The new operator (valid only in C++) allocates a new chunk of memory to hold a variable of type <em>type</em> and returns a pointer to that memory. An optional initializer can be used to initialize the memory. Allocating arrays can be accomplished by providing a <em>size</em> parameter in brackets.</p> <p>The optional <em>arg-list</em> parameter can be used with any of the other formats to pass a variable number of arguments to an overloaded version of new(). For example, the following code shows how the new() function can be overloaded for a class and then passed arbitrary arguments:</p> <pre class="example-code"> class Base { public: Base() { } void *operator new( unsigned int size, string str ) { cout << "Logging an allocation of " << size << " bytes for new object '" << str << "'" << endl; return malloc( size ); } int var; double var2; }; ... Base* b = new ("Base instance 1") Base;</pre> <p>If an int is 4 bytes and a double is 8 bytes, the above code generates the following output when run:</p> <pre class="example-code"> Logging an allocation of 12 bytes for new object 'Base instance 1'</pre> <div class="related-name-format"> Related topics: </div> <div class="related-content"> <a href="delete.html">delete</a><br> (Standard C Memory) <a href="../stdmem/free.html">free</a><br> (Standard C Memory) <a href="../stdmem/malloc.html">malloc</a> </div> </div> </td> </tr> </table></body></html>⌨️ 快捷键说明
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