WorksheetPage test = Project.WorksheetPages("Book1");
Worksheet wks = test.Layers(0);
char str[] = 
 “Buddy, you're a boy, make a big noise\n
 Playing in the street, gonna be a big man someday\n
 You got mud on your face, you big disgrace\n
 Kicking your can all over the place, singin'\n
 We will, we will rock you\n
 We will, we will rock you\n”
;

test.SetComment(str);
}

WorksheetPage test = Project.WorksheetPages("Book1");
string str= 
 "Buddy, you're a boy, make a big noise\n"
 "Playing in the street, gonna be a big man someday\n"
 "You got mud on your face, you big disgrace"
 "Kicking your can all over the place, singin'\n"
 "We will, we will rock you\n"
 "We will, we will rock you\n"
;
str.Replace("\n", "\r\n");
test.SetComments(str);

quote:

---

Assuming you have no issue with using string instead of char [].

---

string str="abc";
string str1="efg";
str += " ";
str += str1;

str1 = str;