英文标题截取字数，不分割单词 函数

 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 }