10.21 (上午) 开课一个月零十七天 (PHP基础语法)
<?php $a = 6; echo $a; //注释语法 /* 多行注释 */ //输出语法 echo "hello"; echo "world","dhakj"; //可以输出多个字符串 print "aaa"; //只能输出一个字符串 print_r(); //打印数组 var_dump(); //输出变量及类型 //变量定义 //数据类型,弱类型语言 $a = "hello"; $hello = "world"; echo $$a; //可变变量 //类型转换 $a = 6; $b = (string)$a; //类型转换 settype($a,"string"); //另外方式 var_dump($a); //运算符与表达式 $a = 6; $b = 7; $c = $a == $b; var_dump($c); $a = "hello"; $b = "world"; $c = $a.$b; //拼接字符串用的是点(.) echo $c; $a = 8; @$c = $a/$b; //错误抑制符 echo $c; //php里面的错误信息 //Notice:提醒 //warning:警告 //error:错误 //三元运算符 $a = 4; $b = 5; echo $a==$b?"相等":"不相等"; //语句 //顺序 $a = 5; $b = 6; //分支 if($a==$b) { echo "相等"; } else { echo "不相等"; } switch($a) { case 4: echo "4444"; break; case 5: echo "55555"; break; case 6: echo "66667"; break; default: echo "000000"; } //循环 for($a=0;$a<10;$a++) { echo $a; } while(true) { echo "aaa"; } do { } while() ?>