在字符串中发现字符串的出现

Question

嗨在另一个字符串中查找字符串的最快和最有效的方式是什么？

例如，我有这个文本;

“嘿@ronald和@汤姆我们要去哪里这个周末”

但是我想找到与开始字符串“@”。

感谢

Answer 1

您可以使用正则表达式。

string test = "Hey @ronald and @tom where are we going this weekend"; 

Regex regex = new Regex(@"@[\S]+"); 
MatchCollection matches = regex.Matches(test); 

foreach (Match match in matches) 
{ 
    Console.WriteLine(match.Value); 
} 

将输出：

@ronald 
@tom 

Answer 2

String str = "hallo world" 
int pos = str.IndexOf("wo",0) 

Answer 3

试试这个：

string s = "Hey @ronald and @tom where are we going this weekend"; 
var list = s.Split(' ').Where(c => c.StartsWith("@")); 

Answer 4

你需要使用正则表达式：

string data = "Hey @ronald and @tom where are we going this weekend"; 

var result = Regex.Matches(data, @"@\w+"); 

foreach (var item in result) 
{ 
    Console.WriteLine(item); 
} 

Answer 5

如果你是速度之后：

string source = "Hey @ronald and @tom where are we going this weekend"; 
int count = 0; 
foreach (char c in source) 
    if (c == '@') count++; 

如果你想要一个班轮：

string source = "Hey @ronald and @tom where are we going this weekend"; 
var count = source.Count(c => c == '@'); 

这里How would you count occurrences of a string within a string?