Ruby將字符串像數(shù)字一樣處理.我們用單引號('...')或雙引號("...")將它們括起來.
ruby> "abc"
"abc"
ruby> 'abc'
"abc"
單引號和雙引號在某些情況下有不同的作用.一個由雙引號括起來的字符串允許字符由一個前置的斜杠引出,而且可以用#{}內(nèi)嵌表達式.而
單引號括起來的字符串并不會對字符串作任何解釋;你看到的是什么便是什么.幾個例子:
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的字符串操作比C更靈巧,更直觀.比如說,你可以用+把幾個串連起來,用*把一個串重復(fù)好幾遍:
ruby> "foo" + "bar"
"foobar"
ruby> "foo" * 2
"foofoo"
相比之下,在C里,因為需要精確的內(nèi)存管理,串聯(lián)字符串要笨拙的多:
char *s = malloc(strlen(s1)+strlen(s2)+1);
strcpy(s, s1);
strcat(s, s2);
/* ... */
free(s);
但對于Ruby,我們不需要考慮字符串的空間占用問題,這令到我們可以從煩瑣的內(nèi)存管理中解脫出來.
下面是一些字符串的處理,
串聯(lián):
ruby> word = "fo" + "o"
"foo"
重復(fù):
ruby> word = word * 2
"foofoo"
抽取字符(注意:在Ruby里,字符被視為整數(shù)):
ruby> word[0]
102 # 102 is ASCII code of `f'
ruby> word[-1]
111 # 111 is ASCII code of `o'
(負的索引指從字符串尾算起的偏移量,而不是從串頭.)
提取子串:
ruby> herb = "parsley"
"parsley"
ruby> herb[0,1]
"p"
ruby> herb[-2,2]
"ey"
ruby> herb[0..3]
"pars"
ruby> herb[-5..-2]
"rsle"
檢查相等:
ruby> "foo" == "foo"
true
ruby> "foo" == "bar"
false
注意:在Ruby 1.0里,以上結(jié)果以大寫字母出現(xiàn).
好,讓我們來試試這些特性.下面是一個猜詞的謎題,可能"謎題"這個詞用在下面的東西上太酷了一點;-)
# 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"
現(xiàn)在,別太擔心代碼細節(jié)了.下面是謎題程序運行的一個對話.
% ruby guess.rb
guess? foobar
Sorry, you lose.
guess? quux
Sorry, you lose.
guess? ^D
The word was baz.
(考慮到1/3的成功率,也許我本該做得好一點.)
