1 /// <summary>
2 /// 截取传入的字符串中左侧第 num 个返回.
3 /// </summary>
4 /// <param name="s">要截取的字符串。</param>
5 /// <param name="num">从左侧数起，截取的字符个数。</param>
6 /// <param name="code">当传入的字符数长于截取字符数是，在已截取字符串加上此字符（如“...”）</param>
7 /// <returns></returns>
8 public static string getvalue(string s,int num)
9 {
10 char[] arr = s.ToCharArray();
11 if (s.Length > num)
12 {
13 if (arr[num - 1] == ' ')
14 {
15 return s.Substring(0,num-1);
16 }
17 else if (arr[num] == ' ')
18 {
19
20 return s.Substring(0,num);
21 }
22 else
23 {
24 int index = s.Substring(0, num).LastIndexOf(" ");
25 string str = s.Substring(0, num);
26 return str.Substring(0, str.LastIndexOf(" "));
27 }
28 }
29 else
30 {
31 return s;
32 }
33 }
34 public static string getvalue(string s, int num,string code)
35 {
36 char[] arr = s.ToCharArray();
37 if (s.Length > num)
38 {
39 if (arr[num - 1] == ' ')
40 {
41 return s.Substring(0, num - 1)+code;
42 }
43 else if (arr[num] == ' ')
44 {
45 return s.Substring(0, num)+code;
46 }
47 else
48 {
49 int index = s.Substring(0, num).LastIndexOf(" ");
50 string str = s.Substring(0, num);
51 return str.Substring(0, str.LastIndexOf(" "))+code;
52 }
53 }
54 else
55 {
56 return s;
57 }
58 }
