As the comment says, we’re going to pack the age, gender and height into 15 bits, of the format: AAAAAAAGHHHHHHH Let’s start with this part: (age << 8) To start with, age has this format: age = 00000000AAAAAAA where each A can be 0 or 1. << 8 moves the bits 8 places to the … Read more
The standard guarantees that false converts to zero and true converts to one as integers: 4.7 Integral conversions … If the destination type is bool, see 4.12. If the source type is bool, the value false is converted to zero and the value true is converted to one. So the effect in the example you … Read more
Is this what you are trying to do? Jon Skeet answered this in another site Basically what you want is (for left) (original << bits) | (original >> (32 – bits)) or (for right) (original >> bits) | (original << (32 – bits)) Also, as Mehrdad has already suggested, this only works for uint, which … Read more
First remember that machine words are of fixed size. Say 4, and that your input is: +—+—+—+—+ | a | b | c | d | +—+—+—+—+ Then pushing everything one position to the left gives: +—+—+—+—+ | b | c | d | X | +—+—+—+—+ Question what to put as X? with a … Read more
In this statement: printf(“%d”,~c); the c is converted to int1 type before ~ (bitwise complement) operator is applied. This is because of integer promotions, that are invoked to operand of the ~. In this case an object of unsigned char type is promoted to (signed) int, which is then (after ~ operator evaluation) used by … Read more
First solutions for shifting (shift is the shift distance, must not be negative, a is the operand to be shifted and contains also the result when done). The power table is used by all three shift operations. // table used for shift operations powtab = { 1, 2, 4, 8, 16, 32, 64, 128, 256, … 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
When you write 1 << n You shift the bit combination 000000001 for n times left and thus put n into the exponent of 2: 2^n So 1 << 10 Really is 1024 For a list of say 5 items your for will cycle 32 times.
There’s a specfic reason you’ll sometimes see ~ applied in front of $.inArray. Basically, ~$.inArray(“foo”, bar) is a shorter way to do $.inArray(“foo”, bar) !== -1 $.inArray returns the index of the item in the array if the first argument is found, and it returns -1 if its not found. This means that if you’re … Read more