Definition and usage analysis of PHP function echo()_PHP tutorial

Using Definition and Usage

PHP function echo() outputs one or more strings.

Syntax

echo(strings)

Parameter Description

strings Required. One or more strings to send to the output.

Tips and Notes

Note: echo() is not actually a function, so you don't need to use parentheses with it. However, if you wish to pass one or more arguments to echo(), then using parentheses will cause a parsing error.

Tip: The echo() function is a little faster than the print() function.

Tip: PHP function echo() can use simplified syntax. See examples below.

<ol class="dp-xml">
<li class="alt"><span><span class="tag"><</SPAN><SPAN class=tag-name>html</SPAN><SPAN class=tag>></span><span> </span><span class="tag"><</SPAN><SPAN class=tag-name>body</SPAN><SPAN class=tag>></span><span> </span></span></li>
<li class="alt"><span><span></span><span class="tag"></span><span class="tag-name">php</span><span> $</span><span class="attribute">color</span><span> = </span><span class="attribute-value">"red"</span><span>; </span><span class="tag">?></span></span></li>
<li class="alt"><span><span class="tag"><span class="tag"></span><span> </span><span class="tag"><</SPAN><SPAN class=tag-name>p</SPAN><SPAN class=tag>></span><span>Roses are </span></span></span></li>
<li class="alt"><span><span class="tag"><span></span><span class="tag"></span><span>=$color</span><span class="tag">?></span></span></span></li>
<li class="alt"><span><span class="tag"><span class="tag"><span class="tag"><span class="tag"><span class="tag-name">p</span><span class="tag">></span></span></span></span></span><li class="alt"><span><span class="tag"><span class="tag"><span class="tag"><span class="tag"></span><span> <span class="tag"><span class="tag-name">body</span><span class="tag">></span><span> </span></span></span></span></span></span><li class="alt"><span><span class="tag"><span class="tag"><span class="tag"><span class="tag"><span><span class="tag"><span class="tag-name">html</span><span class="tag">></span><span> </span></span></span></span></span></span></span></span></li></span></li></span></li>
</ol>

1. echo output scalar

<ol class="dp-xml">
<li class="alt"><span><span class="tag"></span><span class="tag-name">php</span><span> </span></span></li>
<li><span>  echo 123adb; //输出正确  </span></li>
<li class="alt"><span>  echo 123abd; //正确  </span></li>
<li><span>  echo "123adb"; //正确  </span></li>
<li class="alt">
<span class="tag">?></span><span> </span>
</li>
</ol>

2. PHP function echo() output variable, constant

<ol class="dp-xml">
<li class="alt"><span><span class="tag"></span><span class="tag-name">php</span><span> </span></span></li>
<li>
<span>$</span><span class="attribute">a</span><span>=</span><span class="attribute-value">"123456"</span><span>;  </span>
</li>
<li class="alt"><span>echo $a;  //正确  </span></li>
<li>
<span>echo "</span><span class="tag"><span class="tag-name">br</span><span class="tag">></span><span>";  </span><li class="alt"><span>echo "$a"; //正确  </span></li>
<li>
<span>echo "</span><span class="tag"><span class="tag-name">br</span><span class="tag">></span><span>";  </span><li class="alt"><span>echo $a;//不正确  </span></li>
<li>
<span>echo "</span><span class="tag"><span class="tag-name">br</span><span class="tag">></span><span>";  </span><li class="alt"><span>echo abcdef;  //也能正确的显示，但是强烈不建议这么做，<br>因为有很多特殊符号这么做不能正确的显示。  </span></li>
<li>
<span>echo "</span><span class="tag"><span class="tag-name">br</span><span class="tag">></span><span>";  </span><li class="alt">
<span>//echo </span><span class="tag"><</SPAN><SPAN class=tag-name>abd</SPAN><SPAN class=tag>></span><span>;  //比如说这样，带了尖括的，就不能用，<br>你可以去了前面的注释试试会不会报错。  </span>
</li>
<li>
<span>echo "</span><span class="tag"><span class="tag-name">br</span><span class="tag">></span><span>";  </span><li class="alt">
<span>$</span><span class="attribute">b</span><span>=</span><span class="attribute-value">10</span><span>;  </span>
</li>
<li><span>echo $b+10; //显示 20  </span></li>
<li class="alt">
<span>echo "</span><span class="tag"><span class="tag-name">br</span><span class="tag">></span><span>";  </span><li><span>echo "$b+10";  </span></li>
<li class="alt">
<span>echo "</span><span class="tag"><span class="tag-name">br</span><span class="tag">></span><span>";  </span><li><span>echo "结果是："."$b"; //这两种写法的效果是一样的。  </span></li>
<li class="alt">
<span>echo "</span><span class="tag"><span class="tag-name">br</span><span class="tag">></span><span>";  </span><li><span>echo "结果是：$b";  //这两种写法的效果是一样的。  </span></li>
<li class="alt">
<span class="tag">?></span><span> </span>
</li></span>
</li></span>
</li></span>
</li></span>
</li></span>
</li></span>
</li></span>
</li></span>
</li>
</ol>

echo "" is different from the PHP function echo(). When double quotes are added, variables and specific symbols will be escaped. When single quotes are added, variables and specific symbols will not be escaped. Symbols are output directly, so using single quotes is faster than using double quotes. If you can do without double quotes, don't use them.

http://www.bkjia.com/PHPjc/446316.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/446316.htmlTechArticleIn use definition and usage PHP function echo() outputs one or more strings. Syntax echo(strings) Parameter Description strings Required. One or more strings to send to the output. Tip...