c# 中字符和ASCII之间的相互转换

string mapIndex = Request.QueryString["map_index"];
string firstIndex = mapIndex.Substring(0,1);
string lastIndex = mapIndex.Substring(1);
string northIndex1 = string.Empty;
if(lastIndex == "1")
else
string northIndex = firstIndex + northIndex1; //向上
string eastIndex1 = string.Empty;
if(firstIndex == "j")
else
string eastIndex = eastIndex1 + lastIndex;