Ruby - 用另一个字符串替换第一次出现的子字符串
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Ruby - replace the first occurrence of a substring with another string
提问by Sayuj
a = "foobarfoobarhmm"
a = "foobarfoobarhmm"
I want the output as `"fooBARfoobarhmm"
我希望输出为“fooBARfoobarhmm”
ie only the first occurrence of "bar" should be replaced with "BAR".
即只有第一次出现的“bar”应该被替换为“BAR”。
回答by Yossi
Use #sub:
使用#sub：
a.sub('bar', "BAR")
回答by tbuehlmann
String#subis what you need, as Yossi already said. But I'd use a Regexp instead, since it's faster:
String#sub正如 Yossi 已经说过的那样，这就是您所需要的。但我会改用正则表达式，因为它更快：
a = 'foobarfoobarhmm'
output = a.sub(/foo/, 'BAR')
回答by Nafaa Boutefer
to replace the first occurrence, just do this:
要替换第一次出现，只需执行以下操作：
str = "Hello World"
str['Hello'] = 'Goodbye'
# the result is 'Goodbye World'
you can even use regular expressions:
你甚至可以使用正则表达式：
str = "I have 20 dollars"
str[/\d+/] = 500.to_s
# will give 'I have 500 dollars'
