📄 operator_precedence.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++ Operator Precedence</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> > C++ Operator Precedence </div> <h3>C++ Operator Precedence</h3> <p>The operators at the top of this list are evaluated first.</p> <table class="code-table"> <tr> <th class="code-table-th">Precedence</th> <th class="code-table-th">Operator</th> <th class="code-table-th">Description</th> <th class="code-table-th">Example</th> <th class="code-table-th">Associativity</th> </tr> <tr> <td class="code-table-td">1</td> <td class="code-table-td"> ::<br> <td class="code-table-td"> Scoping operator<br> <td class="code-table-td"> Class::age = 2;<br> <td class="code-table-td">none</td> </tr> <tr> <td class="code-table-td">2</td> <td class="code-table-td">()<br> []<br> -><br> .<br> ++<br> --</td> <td class="code-table-td">Grouping operator<br> Array access<br> Member access from a pointer<br> Member access from an object<br> Post-increment<br> Post-decrement</td> <td class="code-table-td">(a + b) / 4;<br> array[4] = 2;<br> ptr->age = 34;<br> obj.age = 34;<br> for( i = 0; i < 10; i++ ) ...<br> for( i = 10; i > 0; i-- ) ...</td> <td class="code-table-td">left to right</td> </tr> <tr> <td class="code-table-td">3</td> <td class="code-table-td">!<br> ~<br> ++<br> --<br> -<br> +<br> *<br> &<br> (type)<br> <a href="keywords/sizeof.html">sizeof</a></td> <td class="code-table-td">Logical negation<br> Bitwise complement<br> Pre-increment<br> Pre-decrement<br> Unary minus<br> Unary plus<br> Dereference<br> Address of<br> Cast to a given type<br> Return size in bytes</td> <td class="code-table-td">if( !done ) ...<br> flags = ~flags;<br> for( i = 0; i < 10; ++i ) ...<br> for( i = 10; i > 0; --i ) ...<br> int i = -1;<br> int i = +1;<br> data = *ptr;<br> address = &obj;<br> int i = (int) floatNum;<br> int size = sizeof(floatNum);</td> <td class="code-table-td">right to left</td> </tr> <tr> <td class="code-table-td">4</td> <td class="code-table-td">->*<br> .*</td> <td class="code-table-td">Member pointer selector<br> Member object selector</td> <td class="code-table-td">ptr->*var = 24;<br> obj.*var = 24;</td> <td class="code-table-td">left to right</td> </tr> <tr> <td class="code-table-td">5</td> <td class="code-table-td">*<br> /<br> %</td> <td class="code-table-td">Multiplication<br> Division<br> Modulus</td> <td class="code-table-td">int i = 2 * 4;<br> float f = 10 / 3;<br> int rem = 4 % 3;</td> <td class="code-table-td">left to right</td> </tr> <tr> <td class="code-table-td">6</td> <td class="code-table-td">+<br> -</td> <td class="code-table-td">Addition<br> Subtraction</td> <td class="code-table-td">int i = 2 + 3;<br> int i = 5 - 1;</td> <td class="code-table-td">left to right</td> </tr> <tr> <td class="code-table-td">7</td> <td class="code-table-td"><<<br> >></td> <td class="code-table-td">Bitwise shift left<br> Bitwise shift right</td> <td class="code-table-td">int flags = 33 << 1;<br> int flags = 33 >> 1;</td> <td class="code-table-td">left to right</td> </tr> <tr> <td class="code-table-td">8</td> <td class="code-table-td"><<br> <=<br> ><br> >=</td> <td class="code-table-td">Comparison less-than<br> Comparison less-than-or-equal-to<br> Comparison greater-than<br> Comparison geater-than-or-equal-to</td> <td class="code-table-td">if( i < 42 ) ...<br> if( i <= 42 ) ...<br> if( i > 42 ) ...<br> if( i >= 42 ) ...</td> <td class="code-table-td">left to right</td> </tr> <tr> <td class="code-table-td">9</td> <td class="code-table-td">==<br> !=</td> <td class="code-table-td">Comparison equal-to<br> Comparison not-equal-to</td> <td class="code-table-td">if( i == 42 ) ...<br> if( i != 42 ) ...</td> <td class="code-table-td">left to right</td> </tr> <tr> <td class="code-table-td">10</td> <td class="code-table-td">&</td> <td class="code-table-td">Bitwise AND</td> <td class="code-table-td">flags = flags & 42;</td> <td class="code-table-td">left to right</td> </tr> <tr> <td class="code-table-td">11</td> <td class="code-table-td">^</td> <td class="code-table-td">Bitwise exclusive OR</td> <td class="code-table-td">flags = flags ^ 42;</td> <td class="code-table-td">left to right</td> </tr> <tr> <td class="code-table-td">12</td> <td class="code-table-td">|</td> <td class="code-table-td">Bitwise inclusive (normal) OR</td> <td class="code-table-td">flags = flags | 42;</td> <td class="code-table-td">left to right</td> </tr> <tr> <td class="code-table-td">13</td> <td class="code-table-td">&&</td> <td class="code-table-td">Logical AND</td> <td class="code-table-td">if( conditionA && conditionB ) ...</td> <td class="code-table-td">left to right</td> </tr> <tr> <td class="code-table-td">14</td> <td class="code-table-td">||</td> <td class="code-table-td">Logical OR</td> <td class="code-table-td">if( conditionA || conditionB ) ...</td> <td class="code-table-td">left to right</td> </tr> <tr> <td class="code-table-td">15</td> <td class="code-table-td">? :</td> <td class="code-table-td">Ternary conditional (if-then-else)</td> <td class="code-table-td">int i = (a > b) ? a : b;</td> <td class="code-table-td">right to left</td> </tr> <tr> <td class="code-table-td">16</td> <td class="code-table-td">=<br> +=<br> -=<br> *=<br> /=<br> %=<br> &=<br> ^=<br> |=<br> <<=<br> >>=</td> <td class="code-table-td">Assignment operator<br> Increment and assign<br> Decrement and assign<br> Multiply and assign<br> Divide and assign<br> Modulo and assign<br> Bitwise AND and assign<br> Bitwise exclusive OR and assign<br> Bitwise inclusive (normal) OR and assign<br> Bitwise shift left and assign<br> Bitwise shift right and assign</td> <td class="code-table-td">int a = b;<br> a += 3;<br> b -= 4;<br> a *= 5;<br> a /= 2;<br> a %= 3;<br> flags &= new_flags;<br> flags ^= new_flags;<br> flags |= new_flags;<br> flags <<= 2;<br> flags >>= 2;</td> <td class="code-table-td">right to left</td> </tr> <tr> <td class="code-table-td">17</td> <td class="code-table-td">,</td> <td class="code-table-td">Sequential evaluation operator</td> <td class="code-table-td">for( i = 0, j = 0; i < 10; i++, j++ ) ...</td> <td class="code-table-td">left to right</td> </tr> </table> <p>It is important to note that <strong>there is no specified precedence</strong> for the operation of changing a variable into a value. For example, consider the following code:</p> <pre class="example-code"> float x, result; x = 1; result = x / ++x;</pre> <p>The value of <it>result</it> is not guaranteed to be consistent across different compilers, because it is not clear whether the computer should change the variable <it>x</it> (the one that occurs on the left side of the division operator) before using it. Depending on which compiler you are using, the variable <it>result</it> can either be <strong>1.0</strong> or <strong>0.5</strong>. The bottom line is that you <strong>should not use the same variable multiple times in a single expression when using operators with side effects.</strong></p> </div> </td> </tr> </table></body></html>⌨️ 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 + -