How to delete characters and append strings?

I am adding a new record to XML file, first I'm querying 开发者_Go百科all existing items and storing the count in an int

int number = query.count()

and then increment the number by 1.

number = number + 1;

Now I want to format this value in a string having N00000000 format and the number will occupy the last positions.

Pseudo code:

//declare the format string
sting format = "N00000000"

//calculate the length of number string
int length =number.ToString().Length();

// delete as many characters from right to left as the length of number string
???

// finally concatenate both strings with + operator
???

String output = "N" + String.Format ("00000000", length)

Alternatively if you change your formatstring to "'N'00000000" you can even use:

String output = String.Format (formatString, length)

Which means you can fully specify your output by changing your formatstring without having to change any code.

int i = 123;
string n = "N" + i.ToString().PadLeft(8, '0');

var result = number.ToString("N{0:0000000}");

HTH

You can use the built in ToString overload that takes a custom numeric format string:

string result = "N" + number.ToString("00000000");

Here is a another one ...

result = String.Format("N{0:00000000}",number);