Question

这是一个测试列表（所有错误包括表达式）：

php > isset(1); // integer

Fatal error: Cannot use isset() on the result of an expression (you can use "null !== expression" instead) in php shell code on line 1
php >     isset('string'); // string

Fatal error: Cannot use isset() on the result of an expression (you can use "null !== expression" instead) in php shell code on line 1
php >     isset(null); // null

Fatal error: Cannot use isset() on the result of an expression (you can use "null !== expression" instead) in php shell code on line 1
php >     isset(['q']); // array

Fatal error: Cannot use isset() on the result of an expression (you can use "null !== expression" instead) in php shell code on line 1
php >     isset(1==1); // expression

Fatal error: Cannot use isset() on the result of an expression (you can use "null !== expression" instead) in php shell code on line 1
php > isset("null !== expression")
php > ;

Fatal error: Cannot use isset() on the result of an expression (you can use "null !== expression" instead) in php shell code on line 1

但是在用空测试时：

   empty(1); // integer
   empty('string'); // string
   empty(null); // null
   empty(['q']); // array
   empty(1==1); // expression
   empty("null !== expression");

没有错误..我知道手册中的警告 Warning isset() only works with variables as passing anything else will result in a parse error. For checking if constants are set use the defined() function.

但是想知道为什么反正..为什么会那样？

Answer 1

[解决] 它将作为即将发布的php7补丁的一个功能修复

为什么isset函数与其他函数不一致？

1 个答案: