ImageMagick can do it, although it’s a bit convoluted. One way is: convert img1 img2 -fx “(((255*u)&(255*(1-v)))|((255*(1-u))&(255*v)))/255” img_out (img1,img2,img_out are the two input and single output file names respectively). Explanation It’s a bit ugly (I’m sure someone with more ImageMagick-fu than me could clean it up but it works like this: -fx “xxx” basically says … Read more
Right, the a = NULL and b = NULL bit was the issue as @a_horse_with_no_name indicated. You might also consider this derivative, which doesn’t require the OR operator: create table test ( id integer primary key, a integer, b integer, check ((a IS NULL) != (b IS NULL)) ); Of course that works exclusively with … Read more
The discussion in issue Microsoft/TypeScript#14094 is relevant here. Types in TypeScript are open in the sense that an object has to have at least the properties described by a type for it to match. So the object { value: 7, data: ‘test’, note: ‘hello’ } matches the type { value: number, data: string }, even … Read more
In a bit wise XOR operation: a b a^b ———– 0 0 0 0 1 1 1 0 1 1 1 0 XOR sum refers to successive XOR operations on integers. Suppose you have numbers from 1 to N and you have to find their XOR sum then for N = 6, XOR sum will … Read more
This is what I use: /^(foo|bar){1}$/ See: http://www.regular-expressions.info/quickstart.html under repetition
Repent, 13 7 chars (No file support), 14 char (With file support) Repent is an esoteric stack-based toy language of my own, with inspiration from J, APL, Golfscript and Python. Here is a short solution. I will explain it, but is very late and this is doing my head in, so I’ll explain it and … Read more
For exactly three terms, you can use this expression: (a ^ b ^ c) && !(a && b && c) The first part is true iff one or three of the terms are true. The second part of the expression ensures that not all three are true. Note that the above expression does NOT generalize … Read more
You can use union types along with the never type to achieve this: type IFoo = { bar: string; can?: never } | { bar?: never; can: number }; let val0: IFoo = { bar: “hello” } // OK only bar let val1: IFoo = { can: 22 } // OK only can let val2: … Read more
A ^ 0 == A A ^ A == 0 A ^ B == B ^ A (A ^ B) ^ C == A ^ (B ^ C) (3) and (4) together mean that the order in which numbers are xored doesn’t matter. Which means that, for example, A^B^X^C^B^A^C is equal to A^A ^ B^B … Read more
For Boolean values, they mean the same thing – although there’s a compound assignment operator for XOR: x ^= y; There’s no equivalent compound assignment operator for inequality. As for why they’re both available – it would be odd for XOR not to be available just because it works the same way as inequality. It … Read more