Quotation « String « PHP

1.Double quotation marks allow the parsing of variables
2.Double-quoted string escape sequences
3.Double-quoted strings
4.If you use single quotation marks to enclose the same string, the variable is not substituted:
5.Using forward slashes on Windows
6.Fixing quote escaping in backreference replacements
7.It is safe to use non-escaped Windows-style filenames in your single-quoted strings
8.Various special characters in string assignments