What does the following sentence say?

if (Strtoupper (CHARSET) = = ' GBK ' &&!empty ($key)) {
if (Is_array ($key)) {
$result = Var_export ($key, true);//becomes a string
$result = Iconv (' UTF-8 ', ' GBK ', $result);
Eval ("\ $result = $result;"); /convert back to array
}else {
$result = Iconv (' UTF-8 ', ' GBK ', $key);
}
}
return $result;

What is the meaning of the charset in this sentence, incredible, is it a random string test?
and eval ("\ $result = $result;"); Why can I turn it into a group?

Reply to discussion (solution)

CHARSET is a constant.
The eval () function calculates the string according to the PHP code. Take a look at the description of the function in the manual.

CHARSET is a constant, you can find define (' CHARSET ', XXX); Defined.
Eval is the conversion of strings to code execution.

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