[C#]中String、String[]、List＜string＞相互转换及string成员substring、split简单使用
一、相互转换
1. String > String[]
String s = "a,b,c,d,e";
String[] sArray = s.Split(',');
2. String[] > String
string[] sArray = {"a", "b", "c", "d","e"};
string s = String.Join(",", sArray);
3.String[] > List<String>
string[] sArray = {"a", "b", "c", "d","e"};
List<String> list = new List<string>(sArray);
4.List<String> > String[]
List<String> list = new List<string>();
list.Add("a");
list.Add("b");
list.Add("c");
list.Add("d");
list.Add("e");
string[] sArray = list.ToArray();
备注：String和List<String>之间的转换可以使用String[]来中转完成
二、String常用操作成员
1、常用
2、Substring介绍
Substring（param1，param2）
param1参数是起始位置，这是原字符串的初始位置：注意：是从该位置开始取，但是不包括这个点，
param2参数是结束位置，可以省略，省略的话就是从开始位置一直取到最后，如果不省略，就是取得指定的长度；
Eg：
string a = “abcde.12345”: a.Substring(3,2) 结果为：de
string a = “abcde.12345”: a.Substring(3,2) 结果为：de.12345
string a = “abcde.12345”: a.Substring(a.LastIndexOf('.')+1) 结果为：12345
3、Split分隔符介绍
1、用字符串分隔：
using System.Text.RegularExpressions;
string str="aaajsbbbjsccc";
string[] sArray=Regex.Split(str,"js",RegexOptions.IgnoreCase);
foreach (string i in sArray) Response.Write(i.ToString() + "<br>");
输出结果：
aaa
bbb
ccc
2、用多个字符来分隔：
string str="aaajbbbscccjdddseee";
string[] sArray=str.Split(new char[2] {'j','s'});
foreach(string i in sArray) Response.Write(i.ToString() + "<br>");
输出结果：
aaa
bbb
ccc
ddd
eee
3、用单个字符来分隔：
string str="aaajbbbjccc";
string[] sArray=str.Split('j');
foreach(string i in sArray) Response.Write(i.ToString() + "<br>");
输出结果：
aaa
bbb
ccc
String.Split 方法有6个重载函数：
程序代码
1) public string[] Split(params char[] separator)
2) public string[] Split(char[] separator, int
count)
3)
public string[] Split(char[] separator, StringSplitOptions options)
4)
public string[] Split(string[] separator, StringSplitOptions options)
5)
public string[] Split(char[] separator, int count, StringSplitOptions
options)
6)
public string[] Split(string[] separator, int count, StringSplitOptions
options)
下边我们通过一些实例来说明下怎么使用(以下string words = "1,2.3,,4";)：
1. public string[] Split(params char[]
separator)
程序代码
string[] split = words.Split(new Char[] { ','
});//返回:{"1","2.3","","4"}
string[]
split = words.Split(new Char[] { ',', '.' });//返回:{"1","2","3","","4"}
2. public string[] Split(char[] separator, int
count)
程序代码
string[] split = words.Split(new Char[] { ',', '.' },
2);//返回:{"1","2.3,,4"}
string[]
split = words.Split(new Char[] { ',', '.' }, 6);//返回:{"1","2","3","","4"}
3. public string[] Split(char[] separator,
StringSplitOptions options)
程序代码
string[] split = words.Split(new Char[] { ',', '.' },
StringSplitOptions.RemoveEmptyEntries);//返回:{"1","2","3","4"} 不保留空元素
string[]
split = words.Split(new Char[] { ',', '.' },
StringSplitOptions.None);//返回:{"1","2","3","","4"} 保留空元素
4. public string[] Split(string[] separator,
StringSplitOptions options)
程序代码
string[] split = words.Split(new string[] { ",", "."
}, StringSplitOptions.RemoveEmptyEntries);//返回:{"1","2","3","4"} 不保留空元素
string[]
split = words.Split(new string[] { ",", "." },
StringSplitOptions.None);//返回:{"1","2","3","","4"} 保留空元素
5. public string[] Split(char[] separator, int count,
StringSplitOptions options)
程序代码
string[] split = words.Split(new Char[] { ',', '.' },
2, StringSplitOptions.RemoveEmptyEntries);//返回:{"1","2.3,,4"} 不保留空元素
string[]
split = words.Split(new Char[] { ',', '.' }, 6,
StringSplitOptions.None);//返回:{"1","2","3","","4"} 保留空元素
6. public string[] Split(string[] separator, int
count, StringSplitOptions options)
程序代码
string[] split = words.Split(new string[] { ",", "."
}, 2, StringSplitOptions.RemoveEmptyEntries);//返回:{"1","2.3,,4"} 不保留空元素
string[]
split = words.Split(new string[] { ",", "." }, 6,
StringSplitOptions.None);//返回:{"1","2","3","","4"} 保留空元素
需要注意的是没有重载函数public string[] Split(string[] separator)，所以我们不能像VB.NET那样使用words.Split(",")，而只能使用words.Split(','）
正则匹配拆分字符串提供了5个重载函数：
using System.Text.RegularExpressions;
1.Regex.Split(String,String)
string str = "aaatsbbtscctsdd";
stirng
[]strArray = Regex.Split(str,"ts"); //正则匹配切割(result: "aaa" "bb" "cc"
"dd");
2.Regex.Split(String,String)
string str = "aaatsbbtscctsdd";
stirng
[]strArray = Regex.Split(str,"ts",RegexOptions.IgnoreCase); //正则匹配切割(result: "aaa" "bb" "cc" "dd");
三、应用
1.单字符拆分
string str = "aaatbbscctdd";
string []strArray = str.Split(new char[]{'t'}); 或string []strArray = str.Split('t'); //单字符切割(result : "aaa" "bbscc" "dd")
2.多字符拆分
string str = "aaatbbscctdd";
string []strArray = str.Split(new char[]{'t','s'}); //多字节切割(result : "aaa" "bb" "cc" "dd")
3.字符串拆分
using System.Text.RegularExpressions;
string str = "aaatsbbtscctsdd";
stirng []strArray = Regex.Split(str,"ts",RegexOptions.IgnoreCase); //正则匹配切割且(result: "aaa" "bb" "cc" "dd");
或者
string str = "aaatsbbtscctsdd";
string []strArray = str.Split(new string[]{"ts"}); //字符串切割(result : "aaa" "bb" "cc" "dd")
注意：
1.String.Split方法没有重载String.Split(stirng [])方法，也就是说str.Split("t")或者str.Split(new string[]{"ts","dd"})都是错误的。
2.除了切割单字符可用String.Split('t')外，其它的都必须用String.Split(new char[]{})这样的格式，否则编译会出错。
