单独的数字范围,如果按顺序,然后是连字符,如果顺序中断,则发生逗号字符

Question

我有一个表示页面的字符串1,2,3,4,8,9,10,15.

我想要将其显示为,1-4,8-10,15 即序列中的数字由连字符分隔,连字符由最小和最大数字依次包围.

如果按顺序中断,则范围用逗号分隔.

string pageNos = "5,6,7,9,10,11,12,15,16";
string result=string.Empty;
string[] arr1 = pageNos.Split(',');
int[] arr = new int[arr1.Length];

for (int x = 0; x < arr1.Length; x++) // Convert string array to integer array
{
    arr[x] = Convert.ToInt32(arr1[x].ToString());
}

for (int i = 0; i < arr.Length;i++)
{
    for (int j = i + 1; ; j++)
        if (arr[i] == (arr[j] - 1))
            result += arr[i].ToString() + "-" + arr[j].ToString();
        else
            result += arr[i].ToString() + ",";
}

Console.WriteLine(result);

Answer 1

我认为循环内循环使事情变得更加混乱.尝试只使用一个循环,因为您只需要遍历整个列表一次.

int start,end;  // track start and end
end = start = arr[0];
for (int i = 1; i < arr.Length; i++)
{
    // as long as entries are consecutive, move end forward
    if (arr[i] == (arr[i - 1] + 1))
    {
        end = arr[i];
    }
    else
    {
        // when no longer consecutive, add group to result
        // depending on whether start=end (single item) or not
        if (start == end)
            result += start + ",";
        else
            result += start + "-" + end + ",";

        start = end = arr[i];
    }
}

// handle the final group
if (start == end)
    result += start;
else
    result += start + "-" + end;

演示:http://ideone.com/7HdpS7

Answer 2

一点点 LINQ 会整理一下：

static IEnumerable<Tuple<int, int>> GetRanges(IEnumerable<int> source)
{
   bool started = false;
   int rangeStart = 0, lastItem = 0;

   foreach (int item in source)
   {
      if (!started)
      {
         rangeStart = lastItem = item;
         started = true;
      }
      else if (item == lastItem + 1)
      {
         lastItem = item;
      }
      else
      {
         yield return new Tuple<int, int>(rangeStart, lastItem);
         rangeStart = lastItem = item;
      }
   }

   if (started)
   {
      yield return new Tuple<int, int>(rangeStart, lastItem);
   }
}

static string FormatRange(Tuple<int, int> range)
{
   string format = (range.Item1 == range.Item2) ? "{0:D}" : "{0:D}-{1:D}";
   return string.Format(format, range.Item1, range.Item2);
}

string pageNos = "5,6,7,9,10,11,12,15,16";
int[] pageNumbers = Array.ConvertAll(pageNos.Split(','), Convert.ToInt32);
string result = string.Join(",", GetRanges(pageNumbers).Select(FormatRange));