Regular Strings
Open strings are a simpler and beautiful way to represent textual data. In many cases, open strings do not fit. One such issue is, they can't start with whitespace, contain structural characters such as colon (:), comma (,), or supports complex escaping. Regular strings solve this problem by letting the user enclose the string in the quotation marks (" U+0022). This makes a regular string look similar to the strings found in most programming languages.
Regular string preserves the whitespace, and structural characters if enclosed within the double quotes!
A Regular String Walkthrough
Some of the examples of regular strings are...
A string with leading and trailing white spaces
A single quote within the regular strings doesn’t cause termination.
Regular string represented using the Unicode characters.
The new-line characters such as line-feed and carriage-return in the string are preserved while parsing.
Escaping
Any character may be escaped using a regular string. The Regular String format support escaping any characters. The control characters and the double quotes inside the string must be escaped.
If the character is among the special code point
All the characters in the special code point shown in the table below may be escaped by placing Reverse solidus (\ U+005C) before that character. If the character is among the special code points and it is a double quotation mark (" U+0022) then it must be escaped.
Caracter
Description
Code Point
"
U+0022
Quotation mark
b
U+0062
Backspace
f
U+0066
Form feed
r
U+0072
Carriage return
n
U+006E
Line feed
t
U+0074
Horizontal tab
u
U+0075
Four-digit Unicode point. Where U is case-insensitive
x
U+0078
Two-digit Unicode point. Where X is
case-insensitive
The character"u" will be escaped only if it is followed by the four-digit hexadecimal number and character "x" will escape if it is followed by the two-digit hexadecimal number.
Escaping special code point characters
Characters that are not included in the above table will not be escaped by the parser by placing Reverse solidus. In the following example, character a will not be escaped as it is not a special code point character. Similarly, character u will not be escaped as it is not followed by a four-digit hexadecimal number.
In the above example, \n and \t will be escaped as it is among the special code point characters.
A double quotation mark within the string must be escaped as shown in the above example because it will cause the string termination.
A backslash before any non-escapable character will not have any effect! In the following example, both values represent "John Doe".
If the character is in the range from (U+0000) to (U+00FF)
If the character is in the Basic Latin Unicode character range i.e from (U+0000) to (U+00FF) then it may be escaped by representing it as the reverse solidus followed by the lower case letter "x", followed by two digits hexadecimal number.
If the character is in the range from (U+0000) to (U+FFFF)
If the character is in the range i.e from (U+0000) to (U+FFFF), then it may be escaped by representing it as a reverse solidus followed by a lower case letter "u", followed by four hexadecimal digits. For example, "\u00AF".
If the character is out of the range from (U+0000) to (U+00FF)
Characters out of the above range are represented as the 12 Character sequence, i.e UTF-16 surrogate pair. So, for example, a string containing only the "🎛" control knobs character (U+1F39B) can be represented as "\uD83C\uDF9B".
String Comparison
The software implementation that parses the Internet Object text requires checking the string values in the objects and their members for equality. In order to achieve interoperability, the software implementations must ensure that the Unicode character units of the transformed textual data are compared code by code numerically with the other string. And at the same time, it must agree on all the cases of equality and inequality of two strings.
In order to compare two strings, the software implementations must first evaluate the strings and convert the escape characters into respective Unicode points and then compare them.
"cafe\u0301"is the same as"café""\u000A"is the same as"\n""\x0A"is the same as"\n"
The emoji of Grinning Face 😀 (U+1F600) is represented using UTF-16 surrogate pair \uD83D\uDE00
"\ud83d\ude00"is the same as"😀""\uD83D\uDE00"is the same as"😀"
The emoji of hundred point symbol "💯" (U+1F4AF) is represented using UTF-16 surrogate pair "\uD83D\uDCAF".
"\ud83d\udcaf"is the same as"💯""\uD83D\uDCAF"is the same as"💯"
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