1.PHP中有两个基本的输出方式：echo和print；
2.echo和print的区别：
**echo:可以输出一个或多个字符串；
**print：只允许输出一个字符串，返回值总为1；
3.echo是一个语言结构，使用的时候可以不用加括号，也可以加上括号：echo或echo()
<?php
echo "<h2>PHP is fun!</h2>";
echo "Hello world!<br>";
echo "I'm about to learn PHP!<br>";
echo "This"," string","was","made","with multiple parameters.";
?>
4.echo命令输出变量和字符串：
<?php
$txt1="Learn PHP";
$txt2="w3cshool.cc";
$cars=array("Volvo","BMW","Toyota");
echo $txt1;
echo "<br>";
echo "Study PHP at $txt2";
echo "My car is a {$cars[0]}";
?>
5.PHP的print语句：print同样是一个语言结构，可以使用括号，也可以不使用括号：print或print();
<?php
print "<h2>PHP is fun!</h2>";
print "Hello world!<br>";
print "I'm about to learn PHP!";
?>