Factorial in Every Language
Published on 01 November 2018 (Updated: 02 May 2020)
The factorial of an integer n
is defined as:
n! = 1 x 2 x 3 x 4 x ... x n
With the special case 0! = 1
.
Requirements
You must write an executable program that accepts an integer n
on standard
input via the command line, and outputs n!
to standard output.
Note that the factorial function grows very quickly. For example, 4! = 24
but 8! = 40320
. Therefore, you should impose a limit on the input, so that
the largest factorial still fits into your language’s largest supported datatype.
Also note that the factorial is not defined for negative integers.
Testing
Some tests for your program are:
Description | Input | Output |
---|---|---|
No input | “Usage: please input a non-negative integer” | |
Empty input | ”” | “Usage: please input a non-negative integer” |
Invalid Input: Not a number | “asdf” | “Usage: please input a non-negative integer” |
Invalid Input: Negative integer | -1 | “Usage: please input a non-negative integer” |
Sample Input: Zero | 0 | 1 |
Sample Input: One | 1 | 1 |
Sample Input: Four | 4 | 24 |
Sample Input: Eight | 8 | 40320 |
Sample Input: Ten | 10 | 3628800 |
Articles
- Factorial in Python on 27 October 2019 by Anuj Singh
Further Reading
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