PHP - 为什么仍然会解析双精度内的单引号变量

Question

Normally, when variables in PHP are enclosed in single quotes, they are treated as strings, i.e

echo '$variable';

will actually echo the word $variable onto the screen.

So why is it then that this string is parsed:

echo "'$variable'";

That code actually does echo the value of the variable. Why is that? It's still inside single quotes, so why does it still get parsed?

Answer 1

Because the single quotes are inside double quotes. Anything inside double quotes gets evaluated. So, your echo statement is passed a string inside double quotes.

This string is evaluated then output. It contains single quotes and a variable.

Try this instead:

<?php
    $var = 10;
    echo '"$var"';
?>