Integer random number generator

How it works

You set a lowest integer and a highest integer. The generator assigns each integer in that closed span a chance to appear. On a fair picker those chances are equal. The output is a whole number, written without a fractional part. A trailing .0 is a costume. Ask the tool which type it actually drew.

This is a number generator with a type constraint, not a different species of chance. The integer part is the constraint. People reach for it when a decimal would be meaningless: seats, tickets, dice faces, array indexes, days in a month you already named. A real-number generator is the wrong sibling for those jobs because 3.7 is not a seat.

Page widgets are typically algorithmic. That is enough for a class, a game, or a sample row. A prize with rules, a secret, or a nonce needs a generator and a process built for those stakes. The word “integer” does not upgrade the stakes. It only forbids fractions.

Whole numbers, not a disguised decimal

If you need 1, 2, 3, 4, or 5, you need five integers. Rounding a real number after the draw is a different method and can pile results on some faces. Do not draw a real number in [1, 5] and round, then call the result a fair integer from 1 to 5, unless you have checked how the rounding treats the edges. Set the tool to integers and skip the costume.

Integers: counting numbers in the span, including negatives if you allowed them. Reals: a continuous span; the wrong type for seats and tickets. With replacement: the next integer may match the last. Without replacement: a deal from the remaining span, until the span is empty.

Negatives are legal if the minimum is negative. Zero is legal if it sits inside the span. A generator that “never returns zero” while zero is inside the span is either broken or filtered. Filtering after the draw changes the weights. If you did not want zero, raise the minimum.

Record the type with the draw

A useful note says “integers from A through B inclusive, N draws, repeats allowed or not.” That note can be replayed as a method even if the next numbers differ. A note that says “we used a random number generator” cannot. The integer constraint is easy to lose in conversation: someone will later assume decimals were allowed, or that 0 was impossible. Write the type down.

An integer generator that keeps printing .5 is not strict. It is a decimal tool in a whole-number hat. When you need unique tickets, deal. When you need independent rolls, roll. When you need names, paste names; encoding people as integers is extra work and extra ways to miscount. The generator is good at integers. It is average at remembering what the integers stood for. That part is your legend, kept beside the output.