串像数字
样处理.我们用单引号('...')或双引号("...")将它们括起来.
ruby> "abc"
"abc"
ruby> 'abc'
"abc"
单引号和双引号在某些情况下有区别
作用.个由双引号括起来串允许由个前置斜杠引出,而且可以用#{}内嵌表达式.而
单引号括起来
串并不会对串作任何解释;你看到是什么便是什么.几个例子:
ruby> pr
"a\nb\nc","\n"
a
c
nil
ruby> pr
'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
串操作比C更灵巧,更直观.比如说,你可以用+把几个串连起来,用*把个串重复好几遍:
ruby> "foo" + "bar"
"foobar"
ruby> "foo" * 2
"foofoo"
相比的下,在C里,
需要精确内存管理,串联串要笨拙多:
char *s = malloc(strlen(s1)+strlen(s2)+1);
strcpy(s, s1);
strcat(s, s2);
/* ... */
free(s);
但对于Ruby,我们不需要考虑
串空间占用问题,这令到我们可以从烦琐内存管理中解脱出来.
下面是
些串处理,
串联:
ruby> word = "fo" + "o"
"foo"
重复:
ruby> word = word * 2
"foofoo"
抽取
(注意:在Ruby里,被视为整数):
ruby> word[0]
102 # 102 is ASCII code of `f'
ruby> word[-1]
111 # 111 is ASCII code of `o'
(负
索引指从串尾算起偏移量,而不是从串头.)
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"
检查相等:
ruby> "foo"
"foo"
true
ruby> "foo"
"bar"
false
注意:在Ruby 1.0里,以上结果以大写字母出现.
好,让我们来试试这些特性.下面是
个猜词谜题,可能"谜题"这个词用在下面东西上太酷了点;-)
# save this as guess.rb
words = ['foobar', 'baz', 'quux']
secret = words[rand(3)]
pr
"guess? "
while guess = STDIN.gets
guess.chop!
guess secret
pr
"You win!\n"
pr
"Sorry, you lose.\n"
end
pr
"guess? "
end
pr
"The word was ", secret, ".\n"
现在,别太担心代码细节了.下面是谜题
运行个对话.
% ruby guess.rb
guess? foobar
Sorry, you lose.
guess? quux
Sorry, you lose.
guess? ^D
The word was baz.
(考虑到1/3
成功率,也许我本该做得好点.)
最新评论