判断地址url是以http://开头的

 #region 方法一 判断网址输入格式

            if (txtUrl.Text .Length >=7 && txtUrl.Text.Substring(0, 7) == "http://")

            {

                 labUrl.Visible = false ;

             }

            else

            {

                labUrl.Visible = true;

                labUrl.Text = "格式为：http://...";

             }

            if (txtUrlForLogo.Text .Length >=7 && txtUrlForLogo.Text.Substring(0, 7) == "http://")

            {

                labUrlLogo.Visible = false;

            }

            else

            {

                labUrlLogo.Visible = true;

                labUrlLogo.Text = "格式为：http://...";

             }

                     

            #endregion

            #region 方法二 判断网址输入格式

            if (txtUrl.Text.StartsWith("http://"))// .Substring (0,7) != "http://")

            {

                labUrl.Visible = false;

            }

            else

            {

                labUrl.Visible = true;

                labUrl.Text = "格式为：http://...";

            }

            if (txtUrlForLogo.Text.StartsWith("http://"))

            {

                labUrlLogo.Visible = false;

            }

            else

            {

                labUrlLogo.Visible = true;

                labUrlLogo.Text = "格式为：http://...";

            }

            #endregion