A mask defines which bits you want to keep, and which bits you want to clear. Masking is the act of applying a mask to a value. This is accomplished by doing: Bitwise ANDing in order to extract a subset of the bits in the value Bitwise ORing in order to set a subset of … Read more
Remember that negative numbers are stored as the two’s complement of the positive counterpart. As an example, here’s the representation of -2 in two’s complement: (8 bits) 1111 1110 The way you get this is by taking the binary representation of a number, taking its complement (inverting all the bits) and adding one. Two starts … Read more
Setting a bit Use the bitwise OR operator (|) to set a bit. number |= 1UL << n; That will set the nth bit of number. n should be zero, if you want to set the 1st bit and so on upto n-1, if you want to set the nth bit. Use 1ULL if number … Read more
The or and and operators can’t be expressed as functions because of their short-circuiting behavior: False and some_function() True or some_function() in these cases, some_function() is never called. A hypothetical or_(True, some_function()), on the other hand, would have to call some_function(), because function arguments are always evaluated before the function is called.
Bitwise is useful for things in PHP just like anything else. How about a value that can have multiple states turned on at the same time? <?php // since we’re setting constant values in base10 we must progressively double // them since bitwise operations work in base2. you’ll see why when we output // these … Read more
Bitwise operators come into play when you have to work with byte- or bit-level data. Here I list a handful of examples using bit operations with code samples (in no particular order): 1. They are common and part of many algorithms in cryptography and hash functions (e.g. MD5). 2. They are also often used if … Read more
Cast the number to unsigned and then shift. That will force a 0-fill.
|| is the logical-or operator. See here. It evaluates to true if at least one of the operands is true. You can only use it with boolean operands; it is an error to use it with integer operands. // Example var one = true || bar(); // result is true; bar() is never called var … Read more
There isn’t a built-in operator for this, but you can easily simulate the >>> yourself: >>> def rshift(val, n): return val>>n if val >= 0 else (val+0x100000000)>>n … >>> rshift(-1000, 3) 536870787 >>> rshift(1000, 3) 125 The following alternative implementation removes the need for the if: >>> def rshift(val, n): return (val % 0x100000000) >> … Read more
In the first two cases, the boolean is cast to a number – 1 for true and 0 for false. In the final case, it is a number that is cast to a boolean and any number except for 0 and NaN will cast to true. So your test cases are really more like this: … Read more