string str=b.ToString();//b==9
for(int i=1;i<a;i++)//a==10
{
  str+="0";
}
return str;

------解决方案--------------------
Dim str As String = b & Space(a-1)
str = str.Replace(" ","0")


或者

Dim str As String = (b & Space(a-1)).Replace(" ","0")

------解决方案--------------------
[code=C#]		int a = 10;
		string first = "b";
		string s = first + new string('0', a - first.Length);
		Response.Write(s);/code]

------解决方案--------------------
string.PadRight方法可以解决你的问题
C# code

string str = "forty-two";
char pad = '.';

Console.WriteLine(str.PadRight(15, pad));    // Displays "forty-two......".
Console.WriteLine(str.PadRight(2,  pad));    // Displays "forty-two".

------解决方案--------------------
[code=vb]Activator.CreateInstance(TypeGet, arrObj)[/code]