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
