PHP中关联数组的插值(双引号字符串) [英] Interpolation (double quoted string) of Associative Arrays in PHP

问题描述

内插PHP的字符串索引数组元素(5.3.3，Win32)时 可能不会出现以下现象:

When interpolating PHP's string-indexed array elements (5.3.3, Win32) the following behavior may be expected or not:

$ha = array('key1' => 'Hello to me');

print $ha['key1'];   # correct (usual way)
print $ha[key1];     # Warning, works (use of undefined constant)

print "He said {$ha['key1']}"; # correct (usual way)
print "He said {$ha[key1]}";   # Warning, works (use of undefined constant)

print "He said $ha['key1']";   # Error, unexpected T_ENCAPSED_AND_WHITESPACE
print "He said $ha[ key1 ]";   # Error, unexpected T_ENCAPSED_AND_WHITESPACE
print "He said $ha[key1]";     # !! correct (How Comes?)

有趣的是，最后一行似乎是正确的PHP代码.有什么解释吗? 可以信任此功能吗?

Inerestingly, the last line seems to be correct PHP code. Any explanations? Can this feature be trusted?

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现在发布的要点设置在粗体中，以减少误解.

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The point of the posting now set in bold face in order to reduce misunderstandings.

推荐答案

是的，您可以信任它. 涵盖了所有变量插值方式文档很好.

Yes, you may trust it. All ways of interpolation a variable are covered in the documentation pretty well.

如果您想知道这样做的原因，那么，我不能为您提供帮助.但还是一如既往:PHP很老，并且发展了很多，因此引入了不一致的语法.

If you want to have a reason why this was done so, well, I can't help you there. But as always: PHP is old and has evolved a lot, thus introducing inconsistent syntax.

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