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  1. #include <algorithm>
  2. #include <cctype>
  3. #include <string>
  4. #include <iostream>
  5.  
  6. template <typename InputIterator, typename OutputIterator>
  7. OutputIterator caesar_cipher(InputIterator src_begin, InputIterator src_end, OutputIterator dest_begin, int shift)
  8. {
  9.     const std::string ab("abcdefghijklmnopqrstuvwxyz"); // AlphaBet
  10.     std::string rot_ab(ab); // ROTated AlphaBet
  11.  
  12.     shift %= static_cast<int> (ab.length()); // bring the shift within the length of the alphabet
  13.  
  14.     if (shift < 0)
  15.         std::rotate(rot_ab.rbegin(), rot_ab.rbegin() - shift, rot_ab.rend());
  16.     else
  17.         std::rotate(rot_ab.begin(), rot_ab.begin() + shift, rot_ab.end());
  18.  
  19.     auto rotator = [ab, rot_ab](char c) -> char {
  20.         if (std::isalpha(c))
  21.         {
  22.             if (std::isupper(c))
  23.                 return std::toupper(rot_ab.at(ab.find(std::tolower(c))));
  24.  
  25.             return rot_ab.at(ab.find(c));
  26.         }
  27.  
  28.         return c;
  29.     };
  30.  
  31.     return std::transform(src_begin, src_end, dest_begin, rotator);
  32. }
  33.  
  34. int main() {
  35.     std::string s = "Wkh Txlfn Eurzq Ira Mxpsv Ryhu Wkh Odcb Grj";
  36.  
  37.     caesar_cipher(s.begin(), s.end(), s.begin(), -3);
  38.     std::cout << s << std::endl;
  39. }
Success #stdin #stdout 0s 3064KB
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The Quick Brown Fox Jumps Over The Lazy Dog
https://ideone.com/R75P6v
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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