Below is the example which shows the use of it
String strManipulation="My nick name is jk";
string strclone;
strclone= strManipulation.Clone().ToString();
strManipulation += "sdgfsdgsDG";
strclone += " test";
MessageBox.Show(strclone  + "   "  + strManipulation);

Example
For Trim()
string strtrim = " My nick name is jk ";
MessageBox.Show("-" + strtrim + "-");
strtrim = Trimfunction(strtrim);
strtrim.Trim();
MessageBox.Show("-" + strtrim + "-");

For TrimStart()
string strtrimstart = " My nick name is jk ";
MessageBox.Show("-" + strtrimstart + "-");
strtrim.TrimStart();
MessageBox.Show("-" + strtrimstart + "-");

For Trimend()
string strtrimend = " My nick name is jk ";
MessageBox.Show("-" + strtrimend + "-");
strtrim.Trimend();
MessageBox.Show("-" + strtrimend + "-");