问题描述
我有一个内置于循环中的变量.像这样:
I have a variable that is built in loop. Something like:
$str = "";
for($i = 0; $i < 10; $i++) $str .= "something";
如果省略$ str ="，我会得到未定义的变量通知，但是我认为php在它第一次看到未声明的变量时会自动声明一个变量?
If $str = "" is ommitted, I get undefined variable notice, but I thought php auto-declare a variable the first time it sees undeclared one?
我该怎么做?
推荐答案
由于将自身的值与另一个值连接在一起，所以会得到未定义的变量.
You get the undefined variable because you're concatenating the value of itself with another value.
相当于
因此，它不能说初始值是多少.等效于此:
So, it can't say what's the initial value is. It's the equivalent of this:
[undefined value]和"something"串联的结果是什么?口译员不能说...
What's the result of a concatenation of [undefined value] and "something"? The interpreter can't say...
因此，您必须像以前一样将""放入变量中以初始化变量的值.
So, you have to put "" in the variable first to initiate the variable's value, as you did.
HTH
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