HTML and CSS Reference
Floating-point numbers are fractional numbers such as 123.56 or -2.5. They must
contain a decimal point or an exponent specifier, such as 1.3e-2. The letter “ e ” for expo-
nent notation can be either uppercase or lowercase.
String Literals and Quoting. String literals are rows of characters enclosed in either
double or single quotes. 1 The quotes must be matched. If the string starts with a single
quote, it must end with a matching single quote, and likewise if it starts with a double
quote, it must end with a double quote. Single quotes can hide double quotes, and dou-
ble quotes can hide single quotes:
"This is a string"
'This is another string'
"This is also 'a string' "
'This is "a string"'
An empty set of quotes is called the null string. If a number is enclosed in quotes, it
is considered a string; for example, “5” is a string, whereas 5 is a number.
Strings are called constants or literals. The string value “hello” is called a string con-
stant or literal. To change a string requires replacing it with another string.
Strings can contain escape sequences (a single character preceded with a backslash),
as shown in Table 3.1. Escape sequences are a mechanism for quoting a single character.
Table 3.1 Escape Sequences
What It Represents
Single quotation mark
Double quotation mark
1. Any string without quotation marks surrounding it is considered the name of a variable.