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38 lines
1.2 KiB
Text
38 lines
1.2 KiB
Text
Returns the integer index of the first match for the given argument,
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or +nil+ if none found;
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the search of +self+ is forward, and begins at position +offset+ (in characters).
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With string argument +substring+,
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returns the index of the first matching substring in +self+:
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'foo'.index('f') # => 0
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'foo'.index('o') # => 1
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'foo'.index('oo') # => 1
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'foo'.index('ooo') # => nil
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'тест'.index('с') # => 2
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'こんにちは'.index('ち') # => 3
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With Regexp argument +regexp+, returns the index of the first match in +self+:
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'foo'.index(/o./) # => 1
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'foo'.index(/.o/) # => 0
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With positive integer +offset+, begins the search at position +offset+:
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'foo'.index('o', 1) # => 1
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'foo'.index('o', 2) # => 2
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'foo'.index('o', 3) # => nil
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'тест'.index('с', 1) # => 2
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'こんにちは'.index('ち', 2) # => 3
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With negative integer +offset+, selects the search position by counting backward
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from the end of +self+:
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'foo'.index('o', -1) # => 2
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'foo'.index('o', -2) # => 1
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'foo'.index('o', -3) # => 1
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'foo'.index('o', -4) # => nil
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'foo'.index(/o./, -2) # => 1
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'foo'.index(/.o/, -2) # => 1
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Related: String#rindex.
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