return

问题 //... Some annoying getter ExecutorService es = Executors.newSingleThreadExecutor(); Future<Integer> result = es.submit(new Callable<Integer>() { public Integer call() throws Exception { //Get some value from the SQL database. } }); return result; Okay, I've looked all over. I need to know how I can make this wait until it finishes retrieving a value from a database to return this. 回答1: You use result.get() to wait for the task to finish and to retrieve the result. The API documentation is

问题 #include <iostream> #include <string> using namespace std; string crash() { } int noCrash() { } int main() { crash(); // crashes // noCrash(); // doesn't crash return 0; } The function crash(), crashes with Mingw g++ 4.6.2 and the function noCrash() executes with no issues. Why does the function returning string crash without a return statement? 回答1: Both are undefined behaviors, even noCrash can crash. 回答2: From standard 6.6.3/2 A return statement without an expression can be used only in

问题 I'm studying from this site and came upon this question and answer: Write a sum method which will work properly when invoked using either syntax below. console.log(sum(2,3)); // Outputs 5 console.log(sum(2)(3)); // Outputs 5 //answer function sum(x) { if (arguments.length == 2) { return arguments[0] + arguments[1]; } else { return function(y) { return x + y; }; } } I understand the code in the if statement, but not in the else statement because it's simply returning a function. That function

问题 I am trying to define a 2D array, but I want to do it in a function, here is my code: int** createArray( int columns, int rows) { int** array[rows]; for(int i = 0; i < rows; i++) { array[i] = new int*[columns]; } for(int i = 0; i <columns; i++) { for(int j = 0; j < rows; j++) { array[i][j] = 0; std::cout <<array[i][j]; } std::cout<<"\n"; } return *array; } int main() { int **myArray = createArray(3,5); for(int k =0; k < 5; k++) { if( (myArray[0][k] == 0) && (&myArray[1][k] == 0)) /

问题 This code will compare usernames and passwords that are stored in a text file. I think it is because of the for loop, it is probably simple but I cant see it. public int loginCheck() { //----------------------------------------------------------------- string[] users = File.ReadLines("Username_Passwords").ToArray(); //line of text file added to array //----------------------------------------------------------------- for (int i = 0; i < users.Length; i++) { string[] usernameAndPassword =

问题 I have a a object that when I'm printing that it's returning Promise <Pending> (I've checked the type of getRateable and it is object) getRateable = getRateableEntitiesTx(tx, hashtagList); I can't have access to the value by this : getRateableEntitiesTx(tx, hashtagList).then((res) => {return res}) If it's a Promise why it's not returning the res properly? Thanks in advance for help 回答1: You can't return the value from an async function because the function returns before the value has been

问题 index1 = 0 singlechar = [] def SINGLE_CHAR_VAR(filename): firdict = vars_indents(filename)[0] firtup_keys = firdict.keys() firtup_val = firdict.values() for keys in firtup_keys: for values in firtup_val: index = 0 for index in range(len(values)): firvallist = firtup_val[index] for item in firvallist: if len(item[0]) == 1: singlechar.append({'ERROR_TYPE': 'SINGLE_CHAR_VAR', 'LINE_NUMBER': str(keys),'COLUMN': str(item[1]),'INFO': str(item[0]),'SOURCE_LINE': str(lines[keys - 1])}) else: continue

问题 I have answered my own question - see answer below I'm writing a class, and I want this behavior: a = f(10,20) some_funct(a.row) # some_function is given 10 some_funct(a.col) # some_function is given 20 some_funct(a) # some_function is given a tuple of 10, 20 <-- THIS ONE :) The last behavior is stumping me. I have not seen any examples that cover this. Thus far: class f(object): """Simple 2d object""" row: int col: int def __init__(self, row, col): self.row = row self.col = col Explictly I

问题 I have answered my own question - see answer below I'm writing a class, and I want this behavior: a = f(10,20) some_funct(a.row) # some_function is given 10 some_funct(a.col) # some_function is given 20 some_funct(a) # some_function is given a tuple of 10, 20 <-- THIS ONE :) The last behavior is stumping me. I have not seen any examples that cover this. Thus far: class f(object): """Simple 2d object""" row: int col: int def __init__(self, row, col): self.row = row self.col = col Explictly I

问题 I'm trying to find the next floating point value after a towards a + 1 . My code basically looks like this: if a == 0: a = numpy.nextafter(a,a+1) I expect to get a new a that's the next floating point value, as stated above, but all I get is "Assigning result of a function call, where the function has no return (assignment-from-no-return)". I've double checked my versions of NumPy and Python, and cannot figure out what's wrong. 来源： https://stackoverflow.com/questions/54548783/fixing-no-return