在C中生成固定长度的字符串＃

Question

如何根据c＃中给出的输入生成一个固定长度的字符串。

For example : 
string s="1"; 
string newstring ; 
I want the newstring to be "AB_000001"; 
// Similarly if 
s="xyz"; 
//I want the newstring as 
newstring = "AB_000xyz"; 

Answer 1

String s = "AB_000000"; 
String newString="xyz"; 
s = s.Remove(s.Length - newString.Length, newString.Length); 
s = s + newString; 

Answer 2

string basestr = "AB_000000"; 
string inp = "xyz"; 
string res = basestr.Substring(0, basestr.Length - inp.Length) + inp;