We have learned so much about PHP, what are variable variables in PHP today? How to understand mutable variables? , I wonder if you have fully mastered it. If not, then follow this article to continue learning.
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Variable variables:
$s1 = "abe"; //这是一个变量,里面存储的是字符串"abe" $abc=10, echo S$s1; //??输出10
Understanding:
1, in php , an "S" is always followed by a variable name!
2. Here, the name of the variable output by echo (identified by the -th S) is: $sl, I"abe "
3, so what is output here is sabc, which is 10
4. This variable form in which "$" appears continuously is the so-called "variable variable"
The code is as follows:
<?php $s1 = 'abc' ; //这是一个变量,里面存储的是字符串"abc" $abc= 10; // echo $$s1; //???,输出10 ?>
The running results are as follows:
The code is as follows:
The following demonstrates the flexibility of "variable variables":
The so-called variable variables actually mean that the name of the variable can be "dynamically changed" to obtain different data values
$v1 = 1; $v2 = 12; $v3 = 33; $v4 = 44; $v5 =115; //求这5个变量的和: //其他语言,只能“一个一个”加起来。 $sum = 0; //用于存储总和 for($i = 1; $i <= 5; $i++){ $v ="v".$i; //这里,结果其实只是一个“字符串”,比如"v1","v2" ... $sum += $$v; } echo "<br />sum = $sum"; ?>
Running results As follows:
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