On Thursday, 11 November 2021 at 05:37:05 UTC, Salih Dincer wrote:
is this a issue, do you need to case?```d enum tLimit = 10_000; // (1) true result enum wLimit = 100_000; // (2) wrong result void main() { size_t subTest1 = tLimit; assert(subTest1 == tLimit); /* no error */ size_t subTest2 = wLimit; assert(subTest2 == wLimit); /* no error */ size_t gauss = (tLimit * (tLimit + 1)) / 2; assert(gauss == 50_005_000); /* no error */ gauss = (wLimit * (wLimit + 1)) / 2; assert(gauss == 5_000_050_000); /* failure // Fleeting Solution: enum size_t limit = 100_000; gauss = (limit * (limit + 1)) / 2; assert(gauss == 5_000_050_000); //* no error */ } /* Small Version: void main(){ enum t = 10_000; size_t a = t * t; assert(a == 100_000_000); // No Error enum w = 100_000; size_t b = w * w; assert(b == 10_000_000_000); // Assert Failure } */ ```
Integer overflow. By default an enum is defined as `int` which is limited to 32 bit. `int.max` is 2_147_483_647 which is the biggest number representable with an int.
You can declare the enum to be of a bigger type `enum : long { w = 100_000 };` or you can use `std.bigint` if you don't know the maximum you work with or the library `std.experimental.checkedint` which allows to set the behaviour one wants in case of overflow.
