Because PHP was produced in 1994, its syntax is a mixture of C, Java, Perl and some of his own programming syntax.
So, students who have basic knowledge of Java before will not have too much trouble learning.
"; } /** 上面的for循环的打印结果,如下: iwanghang0 iwanghang1 iwanghang2 iwanghang3 iwanghang4 iwanghang5 */ /** * var_dump 打印一个变量的类型和值 * 看下面3个例子 */ var_dump($name); // 打印结果:string(9) "iwanghang" echo "
x = ".$x."
"; // 打印结果:x = 6 var_dump($x); // 打印结果:int(6) echo "
"; var_dump(666); // 打印结果:int(666) echo "
"; /** * isset 判断真假 */ $nameInit = isset($name); var_dump($nameInit); // 打印结果:bool(true) echo "
"; $nameInit1 = isset($name1); var_dump($nameInit1); // 打印结果:bool(false) echo "
"; /** * 布尔值(真假)判断 */ if(isset($name)){ echo "真
"; // 打印结果:真 }else{ echo "假
"; } if(isset($name1)){ echo "真
"; }else{ echo "假
"; // 打印结果:假 } /** * 为空判断 */ if(empty($name)){ echo "空
"; }else{ echo "非空
"; // 打印结果:非空 } if(empty($name1)){ echo "空
"; // 打印结果:空 }else{ echo "非空
"; } /** * x等于6 * empty($x)为非空 * var_dump(empty($x))返回布尔值为假 * * x1不存在 * empty($x1)为空 * var_dump(empty($x1))返回布尔值为真 */ echo $x."
"; // 打印结果:6 echo "".empty($x)."
"; // 打印结果: var_dump(empty($x)); // 打印结果:bool(false) echo "
------
"; echo "".empty($x1)."
"; // 打印结果:1 var_dump(empty($x1)); // 打印结果:bool(true)
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