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I’m looking for a way to generate a (fairly) unique (non auto-incrementing) 4-digit string using the numbers 0 – 9 for each digit using C#. I can validate uniqueness and generate another number if a dup is found. I had thought about basing the number somehow on the DateTime object’s Ticks property but am having a difficult time putting the pieces together.
Any thoughts or expertise would be much appreciated.
If it doesn’t increment itself, how is it going to be unique the second time?
Is what you’re saying that you want to generate a random 4-digit string from the set of all possible unused 4-digit strings?
If so, the correct approach is usually to generate all possible 4-digit strings, and shuffle them into a random order. Then take them in order as you need new ones.
CLARIFICATION: Other answers suggest simply generating a random 4-digit string and leaving it at that. Presumably you would then check to see whether it was already used, and generate another one if it’s used. This has the potential of having extremely suboptimal performance. Suppose you have already used 9,999 (all but one) of the possible 4-digit strings ranging from 0000 to 9999. To generate the last one, this method may take many, many tries.