运算符

tips：

1、== 是判断相等的符号，但是有的时候会不慎写成=，这个时候编译的时候不会报错，但是这个语句就不会形成约束条件，这个条件下的语句会无条件执行。所以一般将数字写在左边，表达式写在右边，这样万一写错的话就会报错。

2、&&是短路与，一旦前面的表达式错了，就不会执行后面的表达式。 
3、||是短路或，一旦前面的表达式对了，就不会执行后面的表达式。 
如

<code class="hljs perl has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> i = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> j = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span>((++i) < <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span> && (j++) > <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>){    ……}<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">printf</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">%d</span>,<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">%d</span>\n"</span> , i, j);<span class="hljs-regexp" style="color: rgb(0, 136, 0); box-sizing: border-box;">//</span>打印结果为i = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>， j = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>；</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li></ul>

<code class="hljs cpp has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> num = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5</span>；<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span>(!num){    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">printf</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"A"</span>)；}<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span>    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">printf</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"B"</span>);<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//这个函数的意义是 0打印A，非0打印B</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li></ul>

掩码

常量是有符号数，当他和无符号数进行运算的时候，结果会变成有符号数，所以要给常量进行无符号强制转化。如unsigned int

掩码是用来方便位操作（与，或，抑或，左移，右移）的，因为可以与数的机器数进行相与等位操作，得到数字。

<code class="hljs objectivec has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//想要依次得到数字。可以向右移，然后与掩码1相与，也可以向左移，与十六进制的0x80000000相与，此时如果用二进制的，系统可能识别不了。</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//掩码mask的获得方法（例如想得到右边开始m位到n位的值）：</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//将0这个数的二进制数取反，然后向右移32-（n-m+1）位，再向左移m位，（注意转换无符号数） </span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">unsigned</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span>)~(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">unsigned</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span>)<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>>>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">32</span>-(n-m+<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>))<<m<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//还可以2^(n+1)-2^m，直接获取他的二进制数，即掩码</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//有符号数左移用0补齐，而右移用符号位补齐，所以要强制转换成无符号数。</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li></ul>

&运算符

（1）清0特定位（mask中特定位置0，其他位为1，s = s & mask） 
（2）取某位中的指定位（mask特定位置1，其他位为0，s = s & mask）

|(或)运算符

将特定位置1，而其他位不变

^(抑或)运算

(1)不使用中间变量而交换两数 
(2)将特定位取反（mask特定位置1，s = s & mask）

<code class="hljs autohotkey has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">//交换两数而不使用中间变量//抑或的方法<span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">a</span> = <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">a</span> ^ b<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>b = <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">a</span> ^ b<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span><span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">a</span> = <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">a</span> ^ b<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>//加法的方法<span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">a</span> = <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">a</span> + b<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>b = <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">a</span> - b<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span><span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">a</span> = <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">a</span> - b<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>//但是他的缺点就是可能会溢出//乘法的方法//缺点是不能交换<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li></ul>

条件(三目)运算符

<code class="hljs cs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">（表达式）？（结果<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>）：（结果<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>）；<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//根据表达式进行判断，如果表达式是对的，就执行结果1，否则就是结果2</span></code>