Check if User Has Permissions on List or WebSite

if (oWeb.DoesUserHavePermissions(SPBasePermissions.ViewPages))
{
SPList oList = oWeb.Lists[ListName];

if (oList.DoesUserHavePermissions(SPBasePermissions.ViewListItems))
{
// some smart code
}
}

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Code Block # 1

using (SPSite oSite = new SPSite(http://xxx))

{

using (SPWeb oWeb = oSite.RootWeb)

{

if(oWeb.DoesUserHavePermissions( oWeb.RoleDefinitions["Contribute"].BasePermissions))

//Do Something
else
//Do Something

}

}
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Code Block # 2

oWeb.EffectiveBasePermissions== oWeb.RoleDefinitions["Contribute"].BasePermissions