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Strings

Printing

Output a string to the console

Write the string "Hello World!" to STDOUT

haskell

main = putStrLn "Hello World!"

csharp

System.Console.WriteLine("Hello World!")

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?

haskell

import Network.CGI

query = "http://myserver.com/custinfo/edit.php?" ++ formEncode [("mode", "view"), ("fname", "Ron & Jan"), ("lname","Smith")]

string-wrap

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 "> "

Expected output:
> The quick brown fox jumps over the lazy dog. The quick brown fox jumps over t
> he 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 qui
> ck 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 o
> ver the lazy dog. The quick brown fox jumps over the lazy dog.

haskell

wrap str
| length str <= 77 = [str]
| otherwise = [take 77 str] ++ wrap (drop 77 str)

mapM_ putStrLn . map ("> " ++) . wrap . concat . replicate 10 $ "The quick brown fox jumps over the lazy dog. "

Declaration

Define a string containing special characters

Define the literal string "\#{'}${"}/"

haskell

putStrLn "\"\\#{'}${\"}/\""

let special = "\\#{'}${\"}/"

csharp

string verbatim = @"\#{'}${""""}/";
string cStyle = "\\#{'}${\"\"}/";

Define a multiline string

Define the string:

"This

Is

A

Multiline

String"

haskell

s = "This \
\Is \
\A \
\Multiline \
\String"

csharp

string output = "This\nIs\nA\nMultiline\nString";

string output = @"This
Is
A
Multiline
String";

Define a string containing variables and expressions

Given variables a=3 and b=4 output "3+4=7"

haskell

import Text.Printf

main = do
let a = 3
let b = 4
printf "%d+%d=%d" a b (a + b)

a = 3
b = 4
s = show a ++ "+" ++ show b ++ "=" ++ show (a + b)
main = putStrLn s

csharp

int a = 3;
int b = 4;
Console.WriteLine("{0}+{1}={2}", a,b,a+b);

Manipulation

Reverse the characters in a string

Given the string "reverse me", produce the string "em esrever"

haskell

reverse "reverse me"

csharp

var str = "reverse me";
Console.WriteLine(new String(str.Reverse().ToArray()));

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"

haskell

unwords (reverse (words "This is the end, my only friend!"))

csharp

var str = "This is a end, my only friend!";
str = String.Join(" ", str.Split().Reverse().ToArray());
Console.WriteLine(str);

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.

haskell

import Data.List (intercalate)

-- our list of words ["The", "quick", "brown", ...]
dogs = concat$ replicate 10$ words "The quick brown fox jumps over the lazy dog."

-- ["The", "The quick", "The quick brown", ...]
concats = scanl1 (\s v -> s ++ " " ++ v)

-- takes list of words, returns list of lines
wordwrap :: Int -> [String] -> [String]
wordwrap maxwidth [] = []
wordwrap maxwidth ws = sentence : (wordwrap maxwidth restwords)
where
zipped = zip (concats ws) ws
(sentences, rest) = span (\(s,w) -> (length s) <= maxwidth) zipped
sentence = last (map fst sentences)
restwords = map snd rest

main = putStrLn ("> " ++ intercalate "\n> " (wordwrap 76 dogs))

csharp

using System;
using System.Text;
using System.Linq; // used for Array.ToList() extension

public class TextWrapper {

/// <summary>
/// Wrap the given text to a given width.
/// </summary>
/// <param name="text">The text to be wrapped</param>
/// <param name="width">The maximum width of each line</param>
/// <param name="prefix">Begin each line with this prefix</param>
/// <returns>The wrapped text</returns>
public string Wrap(string text, int width, string prefix) {

var words = text.Split(' ').ToList();
var result = new StringBuilder(prefix);

width = width - prefix.Length;
prefix = "\n" + prefix;

int lineSize = 0;
foreach (var word in words) {
int wordLen = word.Length;

// Do we need to start a new line?
if ((lineSize + wordLen) > width) {
result.Remove(result.Length - 1, 1); // remove trailing space
lineSize = 0;
result.Append( prefix );
}

result.Append(word).Append(' ');
lineSize += wordLen + 1;
}

return result.ToString();
}

public static void Main() {
var prefix = "> ";
var sentence = "The quick brown fox jumps over the lazy dog. ";

var text = "";
for (int i = 0; i < 10; i++)
text += sentence;

// The description said lines of length 78, but
// the example was 72...
Console.WriteLine(new TextWrapper().Wrap(text, 72, prefix));
}
}

Remove leading and trailing whitespace from a string

Given the string " hello " return the string "hello".

haskell

unwords (words " hello ")

csharp

string str = " hello ";
str = str.Trim();
Console.WriteLine(str);

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

haskell

Case

Make a string uppercase

Transform "Space Monkey" into "SPACE MONKEY"

haskell

toUpperCase oldstring converted = if oldstring == ""
then converted
else toUpperCase (tail(oldstring)) (converted ++ [Char.toUpper(head(oldstring))])

toUpperCase "Space Monkey" ""

toUpperCase = map Char.toUpper

toUpperCase "Space Monkey"

csharp

string output = "Space Monkey"

System.Console.WriteLine(output.ToUpper())

Make a string lowercase

Transform "Caps ARE overRated" into "caps are overrated"

haskell

import Char
str = map toLower "Caps ARE overRated"

csharp

string str = "Caps ARE overRated";
str = str.ToLower() ;
Console.WriteLine(str);

Capitalise the first letter of each word

Transform "man OF stEEL" into "Man Of Steel"

haskell

import Data.Char

capitalizeWords = unwords . map capitalizeWord . words
where capitalizeWord [] = []
capitalizeWord (c:cs) = toUpper c : map toLower cs

csharp

System.Threading.Thread.CurrentThread.CurrentCulture.TextInfo.ToTitleCase("man OF stEEL".ToLowerInvariant());