title: Find Position Given Number Among Numbers Made 4 7
signature: function find_position_given_number_among_numbers_made_4_7(n)
test_code: 
  
  -- SOLUTION CODE
  -- ============================================
  PLACEHOLDER_CODE_BODY
  
  -- TESTING CODE 
  -- ============================================
  function isCorrect(actual, expected)
      if type(expected) ~= type(actual) then
          return false
      end
      
      if type(expected) == 'table' then
          for k,v_expected in pairs(expected) do
              
              if actual[k] == nil then
                  return false
              end
              local v_actual = actual[k]
              if not isCorrect(v_actual, v_expected) then
                  return false
              end
              actual[k]=nil
          end
      
          if next(actual) then 
              return false
          end
          return true
      else
          return actual == expected
      end
  end
  
  function validateSolution(actual, expected)
      return isCorrect(actual,expected)
  end
  
  function driver(n, expected)
      local exec_result;
      local status, error_msg = pcall(function () 
          exec_result=PLACEHOLDER_FN_NAME(n) 
      end)
      if status then
          if validateSolution(exec_result,expected) then
              return "PASSED"
          end
          return "FAILED"
      else
          return string.format("ERROR=%s",string.gsub(error_msg,".*:[%d]+: ",""))
      end
  end
      
  function main()
      result = driver("7", 2)
      print(string.format("TEST-0...%s",result))
  
      result = driver("305745689", 5)
      print(string.format("TEST-1...%s",result))
  
      result = driver("444", 7)
      print(string.format("TEST-2...%s",result))
  
      result = driver("4", 1)
      print(string.format("TEST-3...%s",result))
  
      result = driver("2074", 5)
      print(string.format("TEST-4...%s",result))
  
      result = driver("27", 2)
      print(string.format("TEST-5...%s",result))
  
      result = driver("447", 8)
      print(string.format("TEST-6...%s",result))
  
      result = driver("255", 0)
      print(string.format("TEST-7...%s",result))
  
      result = driver("10000111111011", 0)
      print(string.format("TEST-8...%s",result))
  
      result = driver("fAKcSDRTNz", 0)
      print(string.format("TEST-9...%s",result))
  
  end
  
  main()
source_py: def find_position_given_number_among_numbers_made_4_7(n):
      i = 0
      j = len(n)
      pos = 0
      while (i < j):
          if (n[i] == '4'):
              pos = ((pos * 2) + 1)
          if (n[i] == '7'):
              pos = ((pos * 2) + 2)
          i = (i + 1)
      return pos
source_cpp: int find_position_given_number_among_numbers_made_4_7(string n) {
    int i = 0, pos = 0;
    while ( n [ i ] != '\0' ) {
      switch ( n [ i ] ) {
        case '4' : pos = pos * 2 + 1;
        break;
        case '7' : pos = pos * 2 + 2;
        break;
      }
      i ++;
    }
    return pos;
  }