c# - 如何找到字符串中特定句子的所有出现？

Question

假设我有这样一个字符串:

string source = "Today is friday! I'm am having trouble programming this. Today is friday! Tomorrow is saturday. Today is friday!"

我想搜索这个字符串，抓取所有说“今天是星期五!”的句子，然后用我刚找到的句子创建一个新字符串。

上述字符串的预期结果是:

string output = "Today is friday!Today is friday!Today is friday!"

编辑:LINQ 不是强制性的。

谢谢!

Answer 1

这是一种非 LINQ 方法:

string str = "Today is friday! I'm am having trouble programming this. Today is friday! Tomorrow is saturday. Today is friday!";

StringBuilder sb = new StringBuilder();
int index = 0;
do
{
    index = str.IndexOf("Today is friday!", index);
    if (index != -1)
    {
        sb.Append("Today is friday!");
        index++;
    }
} while (index != -1);

string repeats = sb.ToString();