1.字符串访问
string str = "ABCD";
str[0] => "A"
str.Length => 4
2.拆分为字符数组
string str ="ABCD";
str.ToCharArray() => ['A','B','C','D']
string str = "A,B,C,D";
str.Split(','); => [A,B,C,D]
3.截取字符串
string str = "ABCD";
str.Substring(1) => "BCD"
str.Substring(1,2) => "BC"
4.匹配索引
string str = "ABCABCD";
str.IndexOf('A') => "0"
str.IndexOf("BCD") => "4"
str.LastIndexOf('C') => 5
str.LastIndexOf("AB") => 3
str.IndexOf('E') => "-1"
str.Contains("ABCD") => true
5.大小写转换
string str = "aBCD";
str.ToLower() => "abcd"
str.ToUpper() => "ABCD"
6.填充对其
string str = "ABCD";
str.PadLeft(6,'_') => "_ABCD"
str.PadRight(6,"_") => "ABCD_"
7.截头去尾
string str = "_AB_CD_";
str.Trim("_") => "AB_CD"
str.TrimStart("_") => "AB_CD_"
str.TrimEnd("_") => "_AB_CD"
8.插入和删除
string str = "ADEF";
str.Insert(1,"BC") => "ABCDEF"
str.Remove(1) => "A"
str.Remove(0,2) => "EF"
9.替换字符
string s = "A_B_C_D"
str.Replace("_","-") => "A-B-C-D"
10. 分割字符串
string str = "AA,BB,CC,DD";
char[] arr = str.Split(",") => ["AA","BB","CC","DD"]
11. 格式化
string.Format("{0}+{1} = {2}",1,2,1+2);
string.Format("{0:yyyy年MM月dd日}",DateTime.Now));
12.链接字符串
string str = "A,B,C,D";
string[] arr = str.Split(',') => ["A","B","C","D"]
string.Concat(arr) => "ABCD"
string.Join(",",arr) => "A,B,C,D"
PS:StringBuilder.Append比string粘贴字符串效率高
当使用"+"这种销毁内存再开辟内存存放新的字符串时,选择StringBuilder.Append速度更快
StringBuilder sb = new StringBuilder();
sb.Append("你好,");
sb.Append("世界");
sb.Tostring();