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Strings
Printing

Output a string to the console

Write the string "Hello World!" to STDOUT
erlang
io:format("Hello, World!~n").

Retrieve a string containing ampersands from the variables in a url

My PHP script first does a query to obtain customer info for a form. The form has first name and last name fields among others. The customer has put entries such as "Ron & Jean" in the first name field in the database. Then the edit form script is called with variables such as

"http://myserver.com/custinfo/edit.php?mode=view&fname=Ron & Jean&lname=Smith".

The script variable for first name $_REQUEST['firstname'] never gets beyond the "Ron" value because of the ampersand in the data.

I have tried various functions like urldecode but all to no avail. I even tried encoding the url before the view screen is painted so that the url looks like "http://myserver/custinfo/edit.php?mode=view&fname="Ronxxnbsp;xxamp;xxnbsp;Jean"&lname=SMITH". (sorry I had to add the xx to replace the ampersand or it didn't display meaningful url contents the browser sees.)

Of course this fails for the same reasons. What is a better approach?
Declaration

Define a string containing special characters

Define the literal string "\#{'}${"}/"
erlang
Special = "\\#{'}\${\"}/",

Define a multiline string

Define the string:
"This
Is
A
Multiline
String"
erlang
Text = "This\nIs\nA\nMultiline\nString",

Define a string containing variables and expressions

Given variables a=3 and b=4 output "3+4=7"
erlang
A = 3, B = 4,
io:format("~B+~B=~B~n", [A, B, (A+B)]).
Manipulation

Reverse the characters in a string

Given the string "reverse me", produce the string "em esrever"
erlang
Reversed = lists:reverse("reverse me"),
Reversed = revchars("reverse me"),

Reverse the words in a string

Given the string "This is a end, my only friend!", produce the string "friend! only my end, the is This"
erlang
Reversed = string:join(lists:reverse(string:tokens("This is the end, my only friend!", " ")), " "),

Text wrapping

Wrap the string "The quick brown fox jumps over the lazy dog. " repeated ten times to a max width of 78 chars, starting each line with "> ", yielding this result:

> The quick brown fox jumps over the lazy dog. The quick brown fox jumps
> over the lazy dog. The quick brown fox jumps over the lazy dog. The
> quick brown fox jumps over the lazy dog. The quick brown fox jumps
> over the lazy dog. The quick brown fox jumps over the lazy dog. The
> quick brown fox jumps over the lazy dog. The quick brown fox jumps
> over the lazy dog. The quick brown fox jumps over the lazy dog. The
> quick brown fox jumps over the lazy dog.
erlang
TextWrap = textwrap(string:copies(Input, 10), 73 - length(Prefix)),
lists:foreach(fun (Line) -> io:format("~s~n", [string:concat(Prefix, Line)]) end, string:tokens(TextWrap, "\n")).

Remove leading and trailing whitespace from a string

Given the string "  hello    " return the string "hello".
erlang
Trimmed = string:strip(S),

Simple substitution cipher

Take a string and return the ROT13 and ROT47 (Check Wikipedia) version of the string.
For example:
String is: Hello World #123
ROT13 returns: Uryyb Jbeyq #123
ROT47 returns: w6==@ (@C=5 R`ab
erlang
rot13(Str) ->
lists:map(fun(A) ->
if
A >= $A, A =< $Z -> ((A - $A + 13) rem 26) + $A;
A >= $a, A =< $z -> ((A - $a + 13) rem 26) + $a;
true -> A
end
end, Str).

rot47(Str) ->
lists:map(fun(A) ->
if
A >= $!, A =< $~ ->
((A - $! + 47) rem 94) + $!;
true -> A
end
end, Str).
Case

Make a string uppercase

Transform "Space Monkey" into "SPACE MONKEY"
erlang
io:format("~s~n", [string:to_upper("Space Monkey")]).

Make a string lowercase

Transform "Caps ARE overRated" into "caps are overrated"
erlang
io:format("~s~n", [string:to_lower("Caps ARE overRated")]).

Capitalise the first letter of each word

Transform "man OF stEEL" into "Man Of Steel"
erlang
Caps = string:join(lists:map(fun(S) -> to_caps(S) end, string:tokens("man OF stEEL", " ")), " "),