variable-assignment

问题 I am doing an assignment where I've got given a program which reads in a data file and spits out the data into an array of bytes, where the first 4 bytes of the array tell you how many people's names it has (the data file contains). Following the rest of the array which holds strings of the names of the people. This array is pointed to by a const void * foo; For example, the first 4 bytes say there are 5 names stored into the array, and the next 4 bytes tell you the address of the person's

问题 I'm a newbie in Pthread programming. I've been trying to use Pthread in a very simple way like this code below, and it works well in my CodeBlock as I already included the dll and bin files. #include <stdio.h> #include <stdlib.h> #include <pthread.h> void *printNumber(void *x); int main(){ pthread_t threadA, threadB, threadC, threadD; pthread_create(&threadA, NULL, printNumber, (void *)"Sponge"); pthread_create(&threadB, NULL, printNumber, (void *)"Star"); pthread_create(&threadC, NULL,

问题 Is there a cleaner way to assign multiple strings to a single variable in php? I current do like this <?php $myStr = ''; $myStr .= 'John'; $myStr .= '<br>'; $myStr .= 'Paul'; $myStr .= '<br>'; $myStr .= 'Ringo'; echo $myStr; ?> I also use HEREDOC. But are there other ways? 回答1: If you have to concatenate lot of data, it may be a good idea to use arrays . It's cleaner (not necessarily more memory efficient). $items = array('Hello', 'How', 'Are', 'You?'); echo implode(' ', $items); 回答2: It can

问题 I have been using the Locals window to check the assignments for procedure level variables. I have recently updated my code to create a set of public-level variables that read certain inputs from the sheets which do not change from project to project. When seeking to check these variables, I do not see them in the Locals window, no doubt because they are not locally-defined variables! Is there an alternative to the Locals Window for Public variables? And if not, how am I supposed to check

问题 My function is supposed to take a string argument as input, and return the rot-13 encoding of the input string. def str_rot_13(string): c = list(string) for num in c: if ord(num) >= ord('a') and ord('z'): if ord(num) >=('m'): ord(num) -=13 else: ord(num) +=13 elif ord(num) >= ord('A') and ord('Z'): if ord(num) >=('M'): ord(num) -=13 else: ord(num) +=13 z += chr(ord(num)) return z It's giving me a "can't assign to function call" error. I'm not sure what I'm doing wrong. Edit : Finally got it

问题 As far as I've been led to understand, x++ is essentially a terser way of saying x = x + 1 . So far, so clear. In front-end Javascript, I've occasionally seen ++x — I seem to remember from a jsPerf test I can no longer find (how does one Google ++ effectively?) that this somehow had a small performance benefit in a particular version of IE, and let it go at that. However I've recently encountered something that speaks of a weird quirk in execution order (JS code): var x = 1; console.log(x++);

问题 I'm trying to implement an algorithm to build a decision tree from a dataset. I wrote a function to calculate the information gain between a subset and a particular partition, then I try all the possible partition and want to choose the "best" partition, in the sense that it's got the lowest entropy. This procedure must be recursive, hence, after the first iteration, it needs to work for every subset of the partition you got in the previous step. These are the data: X = {{1, 0, 1, 1}, {1, 1,

问题 Is there a syntax to capture a result evaluated in a Boolean expression? In other words, what was the result that caused the Boolean to be True? A concrete example - I want the second largest number in a set, regardless of how often the largest number is duplicated: nums = [1, 2, 3, 4, 4] h = nums.pop() while nums.pop() == h: pass print(nums.pop()) Obviously returns 2, because the 3 has gone in evaluating the expression. Is there something like: while (i = nums.pop()) == h: #Do something with

问题 I've got in the habit of using float f = 0.; //with a trailing period when assigning a zero value to a float in C. Should I be using float f = 0.f; //with an explicit float size or just stop messing about and use float f = 0; //with no trailing anything? Where did I pick up that habit and why? Is any version more right or wrong than any other? 回答1: 0.0 and 0. are doubles, not floats. While it is legal to assign doubles to floats in C without an explicit cast, 0.0f or 0.f would be the correct

问题 When i declare string x = new string(new char[0]); It works fine.My question is what value will be assigned to x ? when i check Console.WriteLine(x.CompareTo(null)==0);,it returns false. 回答1: when you assign new char[0], your string is not null. It is empty. you could do: Console.WriteLine(string.IsNullOrEmpty(x)); 回答2: x will be an empty string, the same as x = "" . null and "" are two distinct string values. In particular, null is a null reference, so you cannot call any instance members on