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Open Source Technologies

Notes \r Line feed.
\$ Escape $ sign so that it is not treated as a variable
but as the character $.
\ {Octal #} The character represented by the specified octal #—for
example.\70 represents the letter 8.
\X{Hexadecima #} The character represented by the specified hexadecimal
#—for example, \0×32 represents the letter 2.

An additional feature of double-quoted strings is that certain notations of variables and expressions
can be embedded directly within them. Without going into specifics, here are some examples of
legal strings that embed variables. The references to variables are automatically replaced with
the variables’ values, and if the values aren’t strings, they are converted to their corresponding
string representations (for example, the integer 123 would be first converted to the string
“123”).
“The result is $result\n”

“The array offset $i contains $arr[$i]”

In cases, where you’d like to concatenate strings with values (such as variables and expressions)
and this syntax isn’t sufficient, you can use the . (dot) operator to concatenate two or more
strings. This operator is covered in a later section.

Single Quotes in addition to double quotes, single quotes may also delimit strings. However,
in contrast to double quotes, single quotes do not support all the double quotes’ escaping and
variable substitution.

The following table includes the only two escapings supported by single quotes:

\’ Single quote.
\\ Backslash, used when wanting to represent a backslash
followed by a single quote—for example.\\’.

Example: ‘Hello, World’
‘Today\’s the day’

Here-Docs Here-docs enable you to embed large pieces of text in your scripts, which may
include lots of double quotes and single quotes, without having to constantly escape them. The
following is an example of a here-doc:

<<<THE_END
PHP stands for “PHP: Hypertext Preprocessor”.

The acronym “PHP” is therefore, usually referred to as a recursive acronym
| →because the long form contains the acronym itself.

As this text is being written in a here-doc there is no need to escape the
| →double quotes.

THE_END

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