return-value

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 The problem is basically about to generate a arithmetic expression from a given 'n' numbers , and the expression should be divisible by 101. we can only have +,-,* operators and expression is left associative. I have tried all the available solution on , that are already mentioned on stack overflow, like closing the expressions with else and many more bool calci(int a[],int n,int sum,int pos,char operato[],deque<int>&q,deque<char>&qc) { if(sum%101==0) { //cout<<"sum:"<<sum<<endl; return true;

问题 The problem is basically about to generate a arithmetic expression from a given 'n' numbers , and the expression should be divisible by 101. we can only have +,-,* operators and expression is left associative. I have tried all the available solution on , that are already mentioned on stack overflow, like closing the expressions with else and many more bool calci(int a[],int n,int sum,int pos,char operato[],deque<int>&q,deque<char>&qc) { if(sum%101==0) { //cout<<"sum:"<<sum<<endl; return true;

问题 Hey i have a model which gives diferential return values. But also a value which isnt a differential (z) def model(t, f): x = f[0] y = f[1] dx_dt = 2x*y dy_dt = x**3 z = 2*x return dx_dt, dy_dt, z My solver can solve this equations and give me x and y at the respective time values. t = np.linspace(0, 10, 100) f0 = [2, 1, 0] result = solve_ivp(model, [np.min(t), np.max(t)], f0, t_eval=t) But now i want also my solution for z which should NOT be integrated by the solver. Is there any

问题 I want to use C++11 std::thread . I am writing a code to parse JSON files and the parsing is not dependent on each other. I have 900 files and to increase the speed of execution I want to create as many threads and make the execution parallel. My problem is at the moment the function I want to pass to the std::thread is a function of a class and it returns the parsed object as a JSON object from which I create a std::vector . I googled 'returning values from threads' and I am getting the

问题 I want to use C++11 std::thread . I am writing a code to parse JSON files and the parsing is not dependent on each other. I have 900 files and to increase the speed of execution I want to create as many threads and make the execution parallel. My problem is at the moment the function I want to pass to the std::thread is a function of a class and it returns the parsed object as a JSON object from which I create a std::vector . I googled 'returning values from threads' and I am getting the

问题 I have a return statement inside a try clause: def f(): try: return whatever() finally: pass # How do I get what `whatever()` returned in here? Is it possible to get the return value inside the finally clause? This is more of a theoretical question, so I'm not looking for a workaround like saving it to a variable. 回答1: No, it isn't - the finally clause's content is independent from return mechanics; if you do want to see what value is returned you'd have to do as you mentioned and explicitly

问题 I have a validation class which uses method chaining. I would like to be able to do single checks with TRUE/FALSE like this: if ($obj->checkSomething()) {} But also chain methods like this: if ($obj->checkSomething()->checkSomethingElse()) {} The problem however is that if one method returns FALSE , it will not send back an object and thus breaks the method chaining which ends with this error: Fatal error: Call to a member function checkSomething() on a non-object in ... Do I have to pick

问题 So, this is my first assignment fiddling with functions in C++ - which I thought I understood being as they're rather similar to methods with C#. But, although my main calls my function fine, and the function runs and returns to the main - It doesn't send back the variable information that it called when it returns. I'm not exactly sure what I've done wrong - it appears to be set up appropriately (IE - Like the sample code in my book for a return) Here's the main code... #include <iostream>

问题 So, this is my first assignment fiddling with functions in C++ - which I thought I understood being as they're rather similar to methods with C#. But, although my main calls my function fine, and the function runs and returns to the main - It doesn't send back the variable information that it called when it returns. I'm not exactly sure what I've done wrong - it appears to be set up appropriately (IE - Like the sample code in my book for a return) Here's the main code... #include <iostream>