This is my first php program!

Data Types
|
25
PHP recognizes floating-point numbers written in two different formats. There’s the
one we all use every day:
3.14
0.017
-7.1
but PHP also recognizes numbers in scientific notation:
0.314E1 // 0.314*10
1
, or 3.14
17.0E-3 // 17.0*10
-3
, or 0.017
Floating-point values are only approximate representations of numbers. For exam-
ple, on many systems 3.5 is actually represented as 3.4999999999. This means you
must take care to avoid writing code that assumes floating-point numbers are repre-
sented completely accurately, such as directly comparing two floating-point values
using
==
. The normal approach is to compare to several decimal places:
if (int($a * 1000) == int($b * 1000)) {
// numbers equal to three decimal places
Use the
is_float( )
function (or its
is_real( )
alias) to test whether a value is a float-
ing point number:
if (is_float($x)) {
// $x is a floating-point number
}
Strings
Because strings are so common in web applications, PHP includes core-level support
for creating and manipulating strings. A string is a sequence of characters of arbi-
trary length. String literals are delimited by either single or double quotes:
'big dog'
"fat hog"
Variables are expanded within double quotes, while within single quotes they are
not:
$name = "Guido";
echo "Hi, $name\n";
echo 'Hi, $name';
Hi, Guido
Hi, $name
Double quotes also support a variety of string escapes, as listed in Table 2-2.
Table 2-2. Escape sequences in double-quoted strings
Escape sequence
Character represented
\"
Double quotes
\n
Newline
,ch02.15294 Page 25 Wednesday, March 13, 2002 11:42 AM

---

This is the Title of the Book, eMatter Edition
Copyright © 2002 O’Reilly & Associates, Inc. All rights reserved.