boolean

问题 I have seen similar questions asked, but none have answered my question. I am relatively new to python, and have no idea what i'm doing. 回答1: Use: >>> bool(1) True >>> bool(0) False >>> int(bool(1)) 1 >>> int(bool(0)) 0 Can convert back too. 回答2: Unless you don't want to explicitly use Boolean type variable you don't need to. Python accepts it as True in many expression: print(True == 1) print(False == 0) Out: True True In other cases you can use bool(1) of course. print(bool(1)) print(bool(0

问题 Maybe this is just obvious to everyone but can someone explain where XOR (or Exclusive-OR) got its name from? What does the word Exclusive really mean? Not that it matters, but its just stuck in my head since morning. OR: 0 0 0 0 1 1 1 0 1 1 1 1 XOR: 0 0 0 0 1 1 1 0 1 1 1 0 Is it "exclusively 0 for inputs 1,1", "special version of OR" or something else? 回答1: XOR is an "exclusive OR" because it only returns a "true" value of 1 if the two values are exclusive, i.e. they are both different. 回答2:

问题 I'm writing a code in C++ for a 2D Ising model. Here's what the code should do: Generate random NxN lattice, with each site either +1 or -1 value. Select a site at random If site when flipped (+1 to -1 or -1 to +1) is a state of lower energy, flip state ie. if dE < 0, flip state. If flipped state is of higher energy, flip with acceptance rate w = e^{-b(dE)}. Where dE is the change in energy if state is flipped. 4.Do this for all NxN sites, without repetition. This is considered one sweep. Do

问题 I have numpy array : np.random.seed(100) mask = np.random.choice([True, False], size=(10,3)) print (mask) [[ True True False] [False False False] [ True True True] <- problem - all values True [ True True False] [ True True True] <- problem - all values True [ True False True] [ True False True] [False True True] [ True False False] [False True True]] Need in each row no all values True - so here can be only 0 , 1 or 2 True because 3 'columns' . Ugly solution is: mask[:, -1] = False print

问题 when my app starts music is playing: -(void)playBgMusic { NSString *path = [[NSBundle mainBundle] pathForResource:@"bgmusic" ofType:@"aif"]; theAudio = [[AVAudioPlayer alloc] initWithContentsOfURL:[NSURL fileURLWithPath:path] error:NULL]; theAudio.delegate = self; [theAudio play]; } but he should be able to turn the music off by pressing a button if he presses the button again the music should turn on again. i have: -(IBAction)check { if (isquiet == NO) { [theAudio stop]; isquiet = YES;

问题 When I try to make a very large boolean array using Java, such as: boolean[] isPrime1 = new boolean[600851475144]; I get a possible loss of precision error? Is it too big? 回答1: To store 600 billion bits, you need an absolute minimum address space of 75 gigabytes ! Good luck with that! Even worse, the Java spec doesn't specify that a boolean array will use a single bit of memory for each element - it could (and in some cases does) use more. In any case, I recognise that number from Project

问题 Which value does the default constructor of the bool type return in C++? For instance, writing int i = int(); guarantees that the variable i will be initiated always with 0. I guess such an initialization routine is possible as well: bool b = bool(); But unfortunately I could not find anywhere which value such a default bool constructor is defined to return. Is the variable b always initialized with false or true . 回答1: false . Seen in the C++14 draft N4296, section 8.5 (Initializers),

问题 While I know that by definition a boolean consists of only two states, true or false. I was wondering what value does a boolean have before it is initialized with one of these states. 回答1: It defaults to false. Edit: By popular demand: unless you're using the wrapped Boolean, which defaults to null. – sudhir.j 回答2: If it is a local variable, it is a compiler error to reference it before it was initialized. If it is a field, it is initialized to false. 回答3: public class NewMain { boolean foo;

问题 While I know that by definition a boolean consists of only two states, true or false. I was wondering what value does a boolean have before it is initialized with one of these states. 回答1: It defaults to false. Edit: By popular demand: unless you're using the wrapped Boolean, which defaults to null. – sudhir.j 回答2: If it is a local variable, it is a compiler error to reference it before it was initialized. If it is a field, it is initialized to false. 回答3: public class NewMain { boolean foo;

问题 I would like to count how many times I see two consecutive TRUE values in R. For example, x <- c(T,F,T,T,F,F,T,F,T,F) x [1] TRUE FALSE TRUE TRUE FALSE FALSE TRUE FALSE TRUE FALSE It would count 1 since there is a TRUE at position 3 and TRUE at position 4. If there are more than 2 consecutive TRUE, then I just want to count it only once, ie this vector x <- c(T,F,T,T,T,F,T,F,T,F) x [1] TRUE FALSE TRUE TRUE TRUE FALSE TRUE FALSE TRUE FALSE would still count 1. I started with looking at rle()