Question

正则表达式获取URL参数 c#

string url="ewfsefsefse?courseId=21312&fesf=213";
Regex urlRegex = new Regex(@"(^|\?|&)courseid=\d*(&|$)");
Match m = urlRegex.Match(url.ToLower());
string courseId =string.Empty;
if (m.Success)
{
courseId = m.Value;
}
我获取的是 ?courseId=21312,我只想得到 21312 应该怎么写啊？
url可能情况
1 ewfsefsefse?courseId=21312&fesf=213
2 ewfsefsefse?wefwe=1232&courseId=21312&fesf=213
3 ewfsefsefse?wefwe=1232&courseId=21312

Answer 1

Regex urlRegex = new Regex(@"(?:^|\?|&)courseid=(\d*)(?:&|$)");
...
...
..

courseId = m.Groups[1].Value;

Answer 2

/courseId=(\d+)/