$a[3] = 5;$a["3"] = 6;$a["3.14"] = 7;$a[3.14] = 8;echo $a[3], $a["3"], $a["3.14"], $a[3.14];
输出为什么是 8878？
回复内容：
$a[3] = 5;$a["3"] = 6;$a["3.14"] = 7;$a[3.14] = 8;echo $a[3], $a["3"], $a["3.14"], $a[3.14];
输出为什么是 8878？
http://php.net/manual/en/language.typ…
Additionally the following key casts will occur:
…..
Floats are also cast to integers, which means that the fractional part will be truncated. E.g. the key 8.7 will actually be stored under 8.
—–
in you case, the 3.14 out of $a[3.14] will be cast to 3
————–
Strings containing valid integers will be cast to the integer type. E.g. the key “8” will actually be stored under 8.
$a[3] = 5;
$a[“3”] = 6;
both are same thing and will be cast to $a[3].
—-
On the other hand “08” will not be cast, as it isn’t a valid decimal integer.
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$a[“3.14″] = 7; //”3.14” is a string and it won’t be cast.
—————
Summary:
$a[3] = 5;
$a[“3”] = 6; // $a[3] is 6 now.
$a[“3.14″] = 7; //”3.14” is a string, no cast then.
$a[3.14] = 8; // 3.14 will be cast to 3 which results in $a[3] = 8
echo $a[3], $a[“3”], $a[“3.14”], $a[3.14];
is actually
echo $a[3],$a[3],$a[“3.14”],$a[3]
想起了学生时代,呵呵. 经常看这种陷阱题,其实现实中从来没遇到过…….
都用引号吧.
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