Ruby string processing

Ruby processes strings like numbers. We enclose them with single quotation marks ('...') or double quotation marks.

Ruby> "ABC"

"ABC"

Ruby> 'abc'

"ABC"

Single quotation marks and double quotation marks have different functions in some cases. A string enclosed by double quotation marks allows a character to be led out by a front slash, and can be embedded with a #{} expression.

Strings enclosed in single quotes do not explain the strings. What are you looking at? Several examples:

Ruby> Print "A \ Nb \ NC", "\ n"

A

C

Nil

Ruby> Print 'a \ Nb \ n', "\ n"

A \ Nb \ NC

Nil

Ruby> "\ n"

"\ N"

Ruby> '\ N'

"\ N"

Ruby> "\ 001"

"\ 001"

Ruby> '\ 001'

"\ 001"

Ruby> "ABCD # {5*3} EFG"

"ABCD 15 EFG"

Ruby> Var = "ABC"

"ABC"

Ruby> "1234 # {var} 5678"

"1234 ABC 5678"

Ruby's string operations are more agile and intuitive than C. For example, you can use + to concatenate several strings and use * to repeat a string several times:

Ruby> "foo" + "bar"

"Foobar"

Ruby> "foo" * 2

"Foofoo"

In contrast, in C, because precise memory management is required, concatenating strings is much more clumsy:

Char * s = malloc (strlen (S1) + strlen (S2) + 1 );

Strcpy (S, S1 );

Strcat (S, S2 );

/*...*/

Free (s );

But for Ruby, we do not need to consider the space occupation of strings, which frees us from the cumbersome memory management.

Below are some strings for processing,

Series:

Ruby> word = "FO" + "O"

"Foo"

Repeat:

Ruby> word = word * 2

"Foofoo"

Extract characters (Note: In Ruby, the characters are considered as integers ):

Ruby> word [0]

102 #102 is ASCII code of 'F'

Ruby> word [-1]

111 #111 is ASCII code of 'O'

(A negative index refers to the offset calculated from the end of the string, rather than from the string header .)

Extract substrings:

Ruby> herb = "parsley"

"Parsley"

Ruby> herb [0, 1]

"P"

Ruby> herb [-2, 2]

"Ey"

Ruby> herb [0 .. 3]

"Pars"

Ruby> herb [-5...-2]

"RSLE"

Check equal:

Ruby> "foo" = "foo"

True

Ruby> "foo" = "bar"

False

Note: In Ruby 1.0, the above results are displayed with uppercase letters.

Well, let's try these features. The following is a guessing puzzle. Maybe the word "Puzzle" is a little cool in the following ;-)

# Save this as guess. Rb

Words = ['foobar', 'baz', 'quux ']

Secret = words [rand (3)]

Print "Guess? "

While guess = stdin. Gets

Guess. Chop!

If guess = secret

Print "you win! \ N"

Break

Else

Print "sorry, you lose. \ n"

End

Print "Guess? "

End

Print "the word was", secret, ". \ n"

Now, don't worry too muchCodeDetails. The following are puzzles.ProgramA dialog to run.

% Ruby guess. Rb

Guess? Foobar

Sorry, you lose.

Guess? Quux

Sorry, you lose.

Guess? ^ D

The word was Baz.

(Considering the success rate of 1/3, maybe I should have done a little better .)