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<a name="1204492"> </a><font color="#003366" face="Verdana, Arial, Helvetica, sans-serif">20.4 Operators</font>
</h2><hr>
<p>
<a name="1204493"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif">All "C-like" operators on variables are supported, including:</font>
</p>
<ul>
<p> <font size=2 face="Verdana, Arial, Helvetica, sans-serif"><li ><a name="1204494"> </a>relational operators:<font face="Verdana, Arial, Helvetica, sans-serif"><b> </b></font><font face="Verdana, Arial, Helvetica, sans-serif"><b> </b></font><font size=2 face=Courier><strong>==</strong></font> (is equal to), <font size=2 face=Courier><strong>!=</strong></font> (is not equal to),<font size=2 face=Courier><strong> >=</strong></font>, <font size=2 face=Courier><strong><</strong></font>, <font size=2 face=Courier><strong><=</strong></font>,</font></p>
<p> <font size=2 face="Verdana, Arial, Helvetica, sans-serif"><li ><a name="1204496"> </a>arithmetic operators: <font face="Verdana, Arial, Helvetica, sans-serif"><b> </b></font><font size=2 face=Courier><strong>+</strong></font>, <font size=2 face=Courier><strong>-</strong></font>, <font size=2 face=Courier><strong>*</strong></font>, <font size=2 face=Courier><strong>/</strong></font>, <font size=2 face=Courier><strong>%</strong></font> (remainder), <font size=2 face=Courier><strong>>></strong></font>, <font size=2 face=Courier><strong><<</strong></font>,</font></p>
<p> <font size=2 face="Verdana, Arial, Helvetica, sans-serif"><li ><a name="1204497"> </a>pre- and post-increment and decrement: <font size=2 face=Courier><strong>++</strong></font>, <font size=2 face=Courier><strong>--</strong></font>,</font></p>
<p> <font size=2 face="Verdana, Arial, Helvetica, sans-serif"><li ><a name="1204498"> </a>logical operators:<font face="Verdana, Arial, Helvetica, sans-serif"><b> </b></font><font face="Verdana, Arial, Helvetica, sans-serif"><b> </b></font><font size=2 face=Courier><strong>&&</strong></font> (and),<font face="Verdana, Arial, Helvetica, sans-serif"><b> </b></font><font size=2 face=Courier><strong>||</strong></font> (or),<font face="Verdana, Arial, Helvetica, sans-serif"><b> </b></font><font size=2 face=Courier><strong>!</strong></font> (not),</font></p>
<p> <font size=2 face="Verdana, Arial, Helvetica, sans-serif"><li ><a name="1204499"> </a>bitwise operators:<font face="Verdana, Arial, Helvetica, sans-serif"><b> </b></font><font face="Verdana, Arial, Helvetica, sans-serif"><b> </b></font><font size=2 face=Courier><strong>&</strong></font> (and), <font size=2 face=Courier><strong>|</strong></font> (or),<font face="Verdana, Arial, Helvetica, sans-serif"><b> </b></font><font size=2 face=Courier><strong>^</strong></font> (exclusive or), <font size=2 face=Courier><strong>~</strong></font> (not),</font></p>
<p> <font size=2 face="Verdana, Arial, Helvetica, sans-serif"><li ><a name="1204500"> </a><font size=2 face=Courier><strong>+=</strong></font>, <font size=2 face=Courier><strong>-=</strong></font>, <font size=2 face=Courier><strong>>>=</strong></font>, <font size=2 face=Courier><strong><<=</strong></font>, <font size=2 face=Courier><strong>&=</strong></font>, <font size=2 face=Courier><strong>!=</strong></font>, <font size=2 face=Courier><strong>^=</strong></font>, <font size=2 face=Courier><strong>*=</strong></font>, <font size=2 face=Courier><strong>\=</strong></font> and <font size=2 face=Courier><strong>%=</strong></font>.</font></p>
</ul>
<p>
<a name="1204501"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif">Operands must be separated from the operator by spaces. Some operators may also be used with string variables.</font>
</p>
<ul>
<p> <font size=2 face="Verdana, Arial, Helvetica, sans-serif"><li ><a name="1204502"> </a><font size=2 face=Courier><strong>+</strong></font> String concatenation - simply works like "<font size=2 face=Courier><strong>strcat()</strong></font>".</font></p>
<p> <font size=2 face="Verdana, Arial, Helvetica, sans-serif"><li ><a name="1204503"> </a><font size=2 face=Courier><strong>-</strong></font> Removes the second string from the first, if present; if the second string is not a substring in the first, the first is left unchanged.</font></p>
<p> <font size=2 face="Verdana, Arial, Helvetica, sans-serif"><li ><a name="1204504"> </a>Relational operators:<font face="Verdana, Arial, Helvetica, sans-serif"><b> </b></font><font face="Verdana, Arial, Helvetica, sans-serif"><b> </b></font><font size=2 face=Courier><strong>==</strong></font> (is equal to), <font size=2 face=Courier><strong>!=</strong></font> (is not equal to),<font size=2 face=Courier><strong> >=</strong></font>, <font size=2 face=Courier><strong><</strong></font>, <font size=2 face=Courier><strong><=</strong></font>.</font></p>
<p> <font size=2 face="Verdana, Arial, Helvetica, sans-serif"><li ><a name="1204505"> </a><font size=2 face=Courier><strong><<</strong></font>, <font size=2 face=Courier><strong>>></strong></font> These take a string and an integer, for example, <font size=2 face=Courier><strong>"hello world" << 5</strong></font>, and return a specified number of characters from the head/tail of the string, for example<br><font size=2 face=Courier><strong>"hello world" << 5</strong></font> returns "<font size=2 face=Courier><strong>hello</strong></font>", <font size=2 face=Courier><strong>"glove" >> 4</strong></font> returns "<font size=2 face=Courier><strong>love</strong></font>". If more characters are asked for than are present, the whole string is returned.</font></p>
<p> <font size=2 face="Verdana, Arial, Helvetica, sans-serif"><li ><a name="1204506"> </a><font size=2 face=Courier><strong>/</strong></font>, <font size=2 face=Courier><strong>%</strong></font> These chop the tail or head of a string off respectively, given a substring at which to cut, for example, <font size=2 face=Courier><strong>"hello world" / "wor"</strong></font> returns "<font size=2 face=Courier><strong>hello </strong></font>", <font size=2 face=Courier><strong>"chop.me"⌨️ 快捷键说明
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