字符串的截取（公共方法） 

 1 #region 从字符串的指定位置截取指定长度的子字符串
 2         /// <summary>
 3         /// 从字符串的指定位置截取指定长度的子字符串
 4         /// </summary>
 5         /// <param name="str">原字符串</param>
 6         /// <param name="startIndex">子字符串的起始位置</param>
 7         /// <param name="length">子字符串的长度</param>
 8         /// <returns>子字符串</returns>
 9         private static string CutString(string str, int startIndex, int length)
10         {
11             if (startIndex >= 0)
12             {
13                 if (length < 0)
14                 {
15                     length = length * -1;
16                     if (startIndex - length < 0)
17                     {
18                         length = startIndex;
19                         startIndex = 0;
20                     }
21                     else
22                     {
23                         startIndex = startIndex - length;
24                     }
25                 }
26 
27                 if (startIndex > str.Length)
28                 {
29                     return "";
30                 }
31             }
32             else
33             {
34                 if (length < 0)
35                 {
36                     return "";
37                 }
38                 else
39                 {
40                     if (length + startIndex > 0)
41                     {
42                         length = length + startIndex;
43                         startIndex = 0;
44                     }
45                     else
46                     {
47                         return "";
48                     }
49                 }
50             }
51 
52             if (str.Length - startIndex < length)
53             {
54                 length = str.Length - startIndex;
55             }
56 
57             return str.Substring(startIndex, length);
58         }
59        
60         /// <summary>
61         /// 从字符串的指定位置开始截取到字符串结尾的了符串
62         /// </summary>
63         /// <param name="str">原字符串</param>
64         /// <param name="startIndex">子字符串的起始位置</param>
65         /// <returns>子字符串</returns>
66         private static string CutString(string str, int startIndex)
67         {
68             return CutString(str, startIndex, str.Length);
69         }
70         #endregion

 

posted @ 2019-09-23 20:43  醉酒三分醒  阅读(353)  评论(0)    收藏  举报