怎样才能不区分大小写

Question

string fullname=this.File1.PostedFile.FileName;
string filename=fullname.Substring(fullname.LastIndexOf("\\")+1);
string type=filename.Substring(filename.LastIndexOf(".")+1);

if(type=="jpg"||type=="bmp"||type=="gif")
{
this.File1.PostedFile.SaveAs(Server.MapPath("uptupian2")+"\\"+filename);
this.Image1.ImageUrl="uptupian2//"+filename;
}
else
{
Response.Write("<script>alert('你所选择的图片的格式不正确')</script>");
}
怎么样才能让它不区分大小写是jpg的可,是JPG的也可以

Answer 1

compare(string s1,string s2,bool ignorecase)
把第三个参数设为true

Answer 2

string type=filename.Substring(filename.LastIndexOf(".")+1).ToLower();

Answer 3

string type=filename.Substring(filename.LastIndexOf(".")+1).ToLower();