string st="300g/盒";
string[] sArray=st.split("/");
string a=sArray[0];  //300g
string b=sArray[1];  //盒

string str = "Meng_Hai_Peng123";
string[] sArray = str.Split(new char[2] { ‘H‘, ‘_‘ });
string a = sArray[0]; //"Meng";
string b = sArray[1]; //"ai";
string c = sArray[2]; //"Peng123";

string str = "Meng_Hai_Peng123";
string[] sArray = str.Split(new string[] { "_H", "Pe" }, StringSplitOptions.RemoveEmptyEntries);
string a = sArray[0]; //"Meng";
string b = sArray[1]; //"ai_";
string c = sArray[2]; // "ng123";

string str = "Meng_HaiPeng_123";
string a= str.Substring(5,3); //Hai 从第5位开始取数，取到第3位

string str = "Meng_HaiPeng_123";
string a = str.Replace("123", "321"); //Meng_HaiPeng_321

string str = "Meng_HaiPeng_123";
string a = str.Replace("_123", ""); //Meng_HaiPeng