获取字符串和字符c#之间的值

string str = "Hello World";
char c = 'o';
int startIndex = str.IndexOf(c);  // 查找字符在字符串中第一次出现的索引
int endIndex = str.IndexOf(c, startIndex + 1);  // 查找字符在字符串中第二次出现的索引
string value = str.Substring(startIndex + 1, endIndex - startIndex - 1);  // 获取字符和字符串之间的值
Console.WriteLine(value);  // 输出结果为 " Wo"

string str = "Hello World";
char c = 'o';
string pattern = $@"(?<={c}).+?(?={c})";
string value = Regex.Match(str, pattern).Value;  // 获取字符和字符串之间的值
Console.WriteLine(value);  // 输出结果为 " W"

string str = "Hello World";
char c = 'o';
bool start = false;
string value = "";
foreach (char ch in str)
{
    if (ch == c)
    {
        if (start)
        {
            break;
        }
        start = true;
    }
    else if (start)
    {
        value += ch;
    }
}
Console.WriteLine(value);  // 输出结果为 " W"