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almokhtar bekkour
almokhtar bekkour

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Check if string is palindrome without String#reverse

#ruby #palindrome 
def palindrome?(str) reversed_str = '' i = str.length - 1 while i >= 0 reversed_str += str[i] i -= 1 end reversed_str == str end
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specs

describe "palindrome?" do it "should accept a string as an arg" do expect { palindrome?("tot") }.to_not raise_error end context "when the string is the same forwards and backwards" do it "should return true" do expect(palindrome?("tot")).to eq(true) expect(palindrome?("racecar")).to eq(true) expect(palindrome?("madam")).to eq(true) expect(palindrome?("aa")).to eq(true) expect(palindrome?("a")).to eq(true) end end context "when the string is not the same forwards and backwards" do it "should return false" do expect(palindrome?("cat")).to eq(false) expect(palindrome?("greek")).to eq(false) expect(palindrome?("xabcx")).to eq(false) end end it "should not use String#reverse" do expect_any_instance_of(String).to_not receive(:reverse) palindrome?("tot") end end
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Ben Sinclair •

If this was for a test, to see if you could check whether a string was a palindrome without using an explicit reverse method, then I'd say it was against the spirit of the question to write your own reverse function. I guess it's a contrived interview type problem, and I think if I was conducting the interview I'd want to see something different.

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