📄 all.html
字号:
<!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>C/C++ Keywords</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> </div><hr> <div class="name-format"> asm </div> <div class="syntax-name-format"> Syntax: </div> <pre class="syntax-box"> asm( "instruction" );</pre> <p>The asm command allows you to insert assembly language commands directly into your code. Various different compilers allow differing forms for this command, such as</p> <pre class="example-code"> asm { instruction-sequence } </pre> <p>or</p> <pre class="example-code"> asm( instruction ); </pre> </div> </td> </tr> </table></body></html><hr> <div class="name-format"> auto </div> <p>The keyword auto is used to declare local variables, and is purely optional.</p> <div class="related-name-format"> Related topics: </div> <div class="related-content"> <a href="register.html">register</a> </div> </div> </td> </tr> </table></body></html><hr> <div class="name-format"> bool </div> <p>The keyword bool is used to declare Boolean logic variables; that is, variables which can be either true or false.</p> <p>For example, the following code declares a boolean variable called <em>done</em>, initializes it to false, and then loops until that variable is set to true.</p> <pre class="example-code"> bool done = false; while( !done ) { ... } </pre> <p>Also see the <a href="../data_types.html">data types</a> page.</p> <div class="related-name-format"> Related topics: </div> <div class="related-content"> <a href="char.html">char</a><br> <a href="double.html">double</a><br> <a href="false.html">false</a><br> <a href="float.html">float</a><br> <a href="int.html">int</a><br> <a href="long.html">long</a><br> <a href="short.html">short</a><br> <a href="signed.html">signed</a><br> <a href="true.html">true</a><br> <a href="unsigned.html">unsigned</a><br> <a href="wchar_t.html">wchar_t</a> </div> </div> </td> </tr> </table></body></html><hr> <div class="name-format"> break </div> <p>The break keyword is used to break out of a <a href= "do.html">do</a>, <a href="for.html">for</a>, or <a href= "while.html">while</a> loop. It is also used to finish each clause of a <a href="switch.html">switch</a> statement, keeping the program from "falling through" to the next case in the code. An example:</p> <pre class="example-code"> while( x < 100 ) { if( x < 0 ) break; cout << x << endl; x++; } </pre> <p>A given break statement will break out of only the closest loop, no further. If you have a triply-nested for loop, for example, you might want to include extra logic or a <a href="goto.html">goto</a> statement to break out of the loop.</p> <div class="related-name-format"> Related topics: </div> <div class="related-content"> <a href="continue.html">continue</a><br> <a href="do.html">do</a><br> <a href="for.html">for</a><br> <a href="goto.html">goto</a><br> <a href="switch.html">switch</a><br> <a href="while.html">while</a> </div> </div> </td> </tr> </table></body></html><hr> <div class="name-format"> case </div> <p>The case keyword is used to test a variable against a certain value in a <a href="switch.html">switch</a> statement.</p> <div class="related-name-format"> Related topics: </div> <div class="related-content"> <a href="default.html">default</a><br> <a href="switch.html">switch</a> </div> </div> </td> </tr> </table></body></html><hr> <div class="name-format"> catch </div> <p>The catch statement handles exceptions generated by the <a href= "throw.html">throw</a> statement.</p> <div class="related-name-format"> Related topics: </div> <div class="related-content"> <a href="throw.html">throw</a><br> <a href="try.html">try</a> </div> </div> </td> </tr> </table></body></html><hr> <div class="name-format"> char </div> <p>The char keyword is used to declare character variables. For more information about variable types, see the <a href= "../data_types.html">data types</a> page.</p> <div class="related-name-format"> Related topics: </div> <div class="related-content"> <a href="bool.html">bool</a><br> <a href="double.html">double</a><br> <a href="float.html">float</a><br> <a href="int.html">int</a><br> <a href="long.html">long</a><br> <a href="short.html">short</a><br> <a href="signed.html">signed</a><br> <a href="unsigned.html">unsigned</a><br> <a href="void.html">void</a><br> <a href="wchar_t.html">wchar_t</a> </div> </div> </td> </tr> </table></body></html><hr> <div class="name-format"> class </div> <div class="syntax-name-format"> Syntax: </div> <pre class="syntax-box"> class class-name : inheritance-list { private-members-list; protected: protected-members-list; public: public-members-list; } object-list;</pre> <p>The class keyword allows you to create new classes. <em>class-name</em> is the name of the class that you wish to create, and <em>inheritance-list</em> is an optional list of classes inherited by the new class. Members of the class are private by default, unless listed under either the protected or public labels. <em>object-list</em> can be used to immediately instantiate one or more instances of the class, and is also optional. For example:</p> <pre class="example-code"> class Date { int Day; int Month; int Year; public: void display(); }; </pre> <div class="related-name-format"> Related topics: </div> <div class="related-content"> <a href="friend.html">friend</a><br> <a href="private.html">private</a><br> <a href="protected.html">protected</a><br> <a href="public.html">public</a><br> <a href="struct.html">struct</a><br> <a href="this.html">this</a><br> <a href="typename.html">typename</a><br> <a href="union.html">union</a><br> <a href="virtual.html">virtual</a> </div> </div> </td> </tr> </table></body></html><hr> <div class="name-format"> const </div> <p>The const keyword can be used to tell the compiler that a certain variable should not be modified once it has been initialized.</p> <p>It can also be used to declare functions of a class that do not alter any class data.</p> <div class="related-name-format"> Related topics: </div> <div class="related-content"> <a href="const_cast.html">const_cast</a><br> <a href="mutable.html">mutable</a> </div> </div> </td> </tr> </table></body></html><hr> <div class="name-format"> const_cast </div> <div class="syntax-name-format"> Syntax: </div> <pre class="syntax-box"> const_cast<type> (object);</pre> <p>The const_cast keyword can be used to remove the <strong>const</strong> or <strong>volatile</strong> property from some variable. The target data type must be the same as the source type, except (of course) that the target type doesn't have to be <a href="const.html">const</a>.</p> <div class="related-name-format"> Related topics: </div> <div class="related-content"> <a href="const.html">const</a><br> <a href="dynamic_cast.html">dynamic_cast</a><br> <a href="reinterpret_cast.html">reinterpret_cast</a><br> <a href="static_cast.html">static_cast</a> </div> </div> </td> </tr> </table></body></html><hr> <div class="name-format"> continue </div> <p>The continue statement can be used to bypass iterations of a given loop.</p> <p>For example, the following code will display all of the numbers between 0 and 20 except 10:</p> <pre class="example-code"> for( int i = 0; i < 21; i++ ) { if( i == 10 ) { continue; } cout << i << " "; } </pre> <div class="related-name-format"> Related topics: </div> <div class="related-content"> <a href="break.html">break</a><br> <a href="do.html">do</a><br> <a href="for.html">for</a><br> <a href="while.html">while</a> </div> </div> </td> </tr> </table></body></html><hr> <div class="name-format"> default </div> <p>A default <a href="case.html">case</a> in the <a href= "switch.html">switch</a> statement.</p> <div class="related-name-format"> Related topics: </div> <div class="related-content"> <a href="case.html">case</a><br> <a href="switch.html">switch</a> </div> </div> </td> </tr> </table></body></html><hr> <div class="name-format"> delete </div> <div class="syntax-name-format"> Syntax: </div> <pre class="syntax-box"> delete p; delete[] pArray;</pre> <p>The delete operator frees the memory pointed to by <em>p</em>. The argument should have been previously allocated by a call to <a href= "new.html">new</a>. The second form of delete should be used to delete an array.</p> <div class="related-name-format"> Related topics: </div> <div class="related-content"> (Standard C Memory) <a href="../stdmem/free.html">free</a><br> (Standard C Memory) <a href="../stdmem/malloc.html">malloc</a><br> <a href="new.html">new</a> </div> </div> </td> </tr> </table></body></html><hr> <div class="name-format"> do </div> <div class="syntax-name-format"> Syntax: </div> <pre class="syntax-box"> do { statement-list; } while( condition );</pre> <p>The do construct evaluates the given <em>statement-list</em> repeatedly, until <em>condition</em> becomes false. Note that every do loop will evaluate its statement list at least once, because the terminating condition is tested at the end of the loop.</p> <div class="related-name-format"> Related topics: </div> <div class="related-content"> <a href="break.html">break</a><br> <a href="continue.html">continue</a><br> <a href="for.html">for</a><br> <a href="while.html">while</a> </div> </div> </td> </tr> </table></body></html><hr> <div class="name-format"> double </div> <p>The double keyword is used to declare double precision floating-point variables. Also see the <a href= "../data_types.html">data types</a> page.</p> <div class="related-name-format"> Related topics: </div> <div class="related-content"> <a href="bool.html">bool</a><br> <a href="char.html">char</a><br> <a href="float.html">float</a><br> <a href="int.html">int</a><br> <a href="long.html">long</a><br> <a href="short.html">short</a><br> <a href="signed.html">signed</a><br> <a href="unsigned.html">unsigned</a><br> <a href="void.html">void</a><br> <a href="wchar_t.html">wchar_t</a> </div> </div> </td> </tr> </table></body></html><hr> <div class="name-format"> dynamic_cast </div> <div class="syntax-name-format"> Syntax: </div> <pre class="syntax-box"> dynamic_cast<type> (object);</pre> <p>The dynamic_cast keyword casts a datum from one type to another, performing a runtime check to ensure the validity of the cast. If you attempt to cast between incompatible types, the result of the cast will be <strong>NULL</strong>.</p> <div class="related-name-format"> Related topics: </div> <div class="related-content"> <a href="const_cast.html">const_cast</a><br> <a href="reinterpret_cast.html">reinterpret_cast</a><br> <a href="static_cast.html">static_cast</a> </div> </div> </td> </tr> </table></body></html><hr> <div class="name-format"> else </div> <p>The else keyword is used as an alternative case for the <a href= "if.html">if</a> statement.</p> <div class="related-name-format"> Related topics: </div> <div class="related-content"> <a href="if.html">if</a> </div> </div> </td> ⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -