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Open Source Technologies

Notes Examples of floating-point numbers include
3.14

+0.9e-2

-170000.5
54.6E42

6.1.2.3 Strings
Strings in PHP are a sequence of characters that are always internally nullterminated. However,
unlike some other languages, such as C, PHP does not rely on the terminating null to calculate
a string’s length, but remembers its length internally. This allows for easy handling of binary
data in PHP—for example, creating an image on-the-fly and outputting it to the browser. The
maximum length of strings varies according to the platform and C compiler, but you can expect
it to support at least 2GB. Don’t write programs that test this limit because you’re likely to first
reach your memory limit.
When writing string values in your source code, you can use double quotes (“), single quotes
(‘) or here-docs to delimit them.

Double Quotes Examples for double quotes:
“PHP: Hypertext Pre-processor”

“GET / HTTP/1.0\n”

“1234567890”
Strings can contain pretty much all characters. Some characters can’t be written as is, however,
and require special notation:

\n Newline
\t Tab.
\” Double quote.
\\ Backslash.
\0 ASCII 0 (null).
\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{Hexadecimal#} The character represented by the specified hexadecimal
#—forexample, \0x32 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”).
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