1. 下面语句输出什么?为什么?
if ($a=$b) printf(“a==b”);
else printf(“a!=b”);
2. $array[‘anykey’]和$array[anykey]有什么区别?
(我的想法:第一题 因为$a=$b ,而$b没赋值,所以两个都为空,输出"a==b".但实际运行时输出"a!=b",这个我就不解了.
第二题 我就不知道这题的用意了,一个索引是字符,一个是变量吧)
回复讨论(解决方案)
1、a!=b
题目没给 $b 赋值所以 $b 空,$a=$b 返回空,进入 false 分枝
2、
$array[‘anykey’] 中的 anykey 是字符串
$array[anykey] 中的 anykey 是常量
当屏蔽了 E_NOTICE 级别错误 时两者一样
我只想说 版主起好早。。
1. $a=$b
因为$b没有值,所以是null,$a=$b后,$a也是null,所以if($a) 为null 即false
如果加一句
$b=1;
if ($a=$b) printf("a==b");
else printf("a!=b");
这样就返回true
2.
$array[‘anykey’]和$array[anykey]
如果没有加单引,系统会在找不到后自动帮你加上再查找一次。所以是一样,不过如果不加会有notice提示,并且需要查多一次导致资源浪费。
1.楼主可以单独输出 $a=$b 的值就知道为什么输出"a!=b"
2.$array[‘anykey’]和$array[anykey],建议用前者,性能高

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