I'm trying to create a sequence of numbers in string format, once I reach "99999" I want to continue the sequence using leading letters.
Example:
"00000" -> "00100" -> "99999" -> "A0001" -> "A9999" -> "B0001" -> "ZZZZZ"
Is there an easy way to achieve this ?
So far I tried to split my string in numbers and letters and then I have some code cheking if numbers reach maximum, if it reach the maximum available I add a letter. Doesn't look really elegant to me.
Let's implement GetNextValue method: for a given value (e.g. "A9999") we compute the next ("B0001"):
private static string GetNextValue(string value) {
StringBuilder sb = new StringBuilder(value);
// Digits only: 1239 -> 1240
for (int i = value.Length - 1; i >= 0; --i) {
if (sb[i] < '9') {
sb[i] = (char)(sb[i] + 1);
return sb.ToString();
}
else if (sb[i] >= 'A')
break;
else
sb[i] = '0';
}
// 1st letter: 9999 -> A001
if (sb[0] == '0') {
sb[0] = 'A';
if (sb[sb.Length - 1] == '0')
sb[sb.Length - 1] = '1';
return sb.ToString();
}
// Leading letters AZ999 -> BA001
for (int i = value.Length - 1; i >= 0; --i) {
if (sb[i] >= 'A') {
if (sb[i] < 'Z') {
sb[i] = (char)(sb[i] + 1);
if (sb[sb.Length - 1] == '0')
sb[sb.Length - 1] = '1';
return sb.ToString();
}
else
sb[i] = 'A';
}
}
// All letters increment: ABCDZ -> ABCEA
for (int i = 0; i < value.Length; ++i) {
if (sb[i] == '0') {
sb[i] = 'A';
if (sb[sb.Length - 1] == '0')
sb[sb.Length - 1] = '1';
return sb.ToString();
}
}
// Exhausting: ZZZZZ -> 00000
return new string('0', value.Length);
}
If you want to enumerate these values:
private static IEnumerable<string> Generator(int length = 5) {
string item = new string('0', length);
do {
yield return item;
item = GetNextValue(item);
}
while (!item.All(c => c == '0'));
}
Demo: (let's use a string of length 3)
Console.Write(string.Join(Environment.NewLine, Generator(3)));
Outcome: (27234 items in total; 18769482 items if length == 5)
000
001
002
...
009
010
...
999
A01
...
A99
B01
...
Z99
AA1
...
AA9
AB1
...
AZ9
BA1
...
ZZ9
AAA
AAB
AAC
...
AAZ
ABA
...
ZZY
ZZZ
Here is an extension method which formats integer values to your format (with leading letters):
public static string ToZormat(this int value, int length = 5)
{
string map = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
char[] result = new char[length];
var x = value;
for(int i = 0; i < length; i++)
{
int threshold = (int)Math.Pow(10, length - i - 1);
var index = Math.Min(map.Length - 1, x / threshold);
result[i] = map[index];
x -= threshold * index;
}
return new String(result);
}
When you have number formatted to a string of length 5, leading letters appear after value 99,999, next go A0,000, ... A9,999, B0,000 etc. As you can see the first character changes every 10,000 numbers. The second character changes every 1,000 numbers. And last, the fifth character will change for every number. We just need to implement that algorithm.
Basic steps:
10,000, 1,000, 100, 10, 1.You should add validation for the max value which fits the given length of the formatted string.
Sample for length 3:
Enumerable.Range(0, 3886).Select(x => x.ToZormat(3))
Output:
000
001
002
...
999
A00
A01
...
A99
B00
B01
...
Z99
ZA0
ZA1
...
ZZ9
ZZA
...
ZZZ
Z9999 -> AA001?AZ999 -> BA001?