PHP array subscript Plus single quote, double quote, and no efficiency comparison

1. Numeric type index is not added.

2. The index of the string type must be added, plus the single quotation mark.

According to the following

In general, but when the index is a number, if passed $arr[' 1 '] will first convert 1 to a number, which will affect the efficiency

If the string is not quoted, if there is a constant and index value equal at this point, the index is converted to a constant value. such as defined ("name", "Zhangsan") $arr [name]---> $arr [Zhangsan]

The string is therefore quoted, and the double quotation marks are parsed for more escape characters and to determine whether a value is a variable. Therefore, the efficiency is lower than the single quotation mark.

PHP array subscript Plus single quote, double quote, and no efficiency comparison