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Define an array in PHP
$sz = Array ();

If you add a specific name element to the array, I write it this way.
$sz [A] = "123456";

And then use the Echo $sz [' a '] to output nothing what is this for? Is there any other way, master help?

------Solution--------------------
Output: Notice:use of undefined constant a-assumed ' a ' in D:\www\test.php on line 3
123456
So the assignment will not be able to ah $sz [' a '] = "123456";

------Solution--------------------
1.
$sz =array (' a ' = ' 123456 ');

2.
$sz =array ();
$sz [' A ']= ' 123456 ';


------Solution--------------------
In general, we set the error checking level of PHP to E_all ^ E_notice so that we can give full play to the flexibility of PHP for variable handling, in this case
$sz = Array ();
$sz [A] = "123456";
echo $sz [' a ']; 123456

Of course, as a traditional programmer, you can set the error checking level to E_all
So
$sz = Array ();
$sz [A] = "123456"; A Notice level error will appear here. If the error display function is not turned on, the program will be terminated.
echo $sz [' a ']; 123456

But you should notice that the error description is
Use of undefined constant a-assumed ' a '
Using constants that are not defined

He pointed out the fact that:
Define (' A ', 1);
$sz = Array ();
$sz [A] = "123456";
echo $sz [1]; 123456

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