function

问题 I should write a function to get some information about the system (the most important information is the the architecture). I found the function uname which can be used including sys/utsname.h . Well, though I googled and I read the documentation, I couldn't find any example of the function and I don't understand how to use uname. Anyone can explain me how to use it? it would be great if you can write an example, too. Thanks in advance. 回答1: First, include the header: #include <sys/utsname.h

问题 #include <iostream> using namespace std; class MyClass { public: void printInformation(); }; void MyClass::printInformation() { return; } int main() { MyClass::printInformation(); fgetc( stdin ); return(0); } How would I call the printInformation function within main ? The error tells me that I need to use a class object to do so. 回答1: Declare an instance of MyClass, and then call the member function on that instance: MyClass m; m.printInformation(); 回答2: If you want to make your code work as

问题 For the code below: (1) "main" calls a function "f1". (2) function "f1" does some number crunching; creates an array of "char" with malloc and then, returns the pointer of the array to the main (without de-allocating -freeing- the array). I have 3 questions related to the case: (1) I assume, although the function "f1" has terminated, the allocated char array still stays allocated until the main program terminates completely. That is, the allocated memory still belongs to the main and no other

问题 For the code below: (1) "main" calls a function "f1". (2) function "f1" does some number crunching; creates an array of "char" with malloc and then, returns the pointer of the array to the main (without de-allocating -freeing- the array). I have 3 questions related to the case: (1) I assume, although the function "f1" has terminated, the allocated char array still stays allocated until the main program terminates completely. That is, the allocated memory still belongs to the main and no other

问题 Suppose I have a dataframe as follows: In [1]: test_dup_df Out[1]: exe_price exe_vol flag 2008-03-13 14:41:07 84.5 200 yes 2008-03-13 14:41:37 85.0 10000 yes 2008-03-13 14:41:38 84.5 69700 yes 2008-03-13 14:41:39 84.5 1200 yes 2008-03-13 14:42:00 84.5 1000 yes 2008-03-13 14:42:08 84.5 300 yes 2008-03-13 14:42:10 84.5 88100 yes 2008-03-13 14:42:10 84.5 11900 yes 2008-03-13 14:42:15 84.5 5000 yes 2008-03-13 14:42:16 84.5 3200 yes I want to group a duplicate data at time 14:42:10 and apply

问题 I've been learning about C++ constexpr functions, and I implemented a constexpr recursive function to find the nth fibonacci number. #include <iostream> #include <fstream> #include <cmath> #include <algorithm> #include <vector> constexpr long long fibonacci(int num) { if (num <= 2) return 1; return fibonacci(num - 1) + fibonacci(num - 2); } int main() { auto start = clock(); long long num = fibonacci(70); auto duration = (clock() - start) / (CLOCKS_PER_SEC / 1000.); std::cout << num << "\n" <

问题 I've been learning about C++ constexpr functions, and I implemented a constexpr recursive function to find the nth fibonacci number. #include <iostream> #include <fstream> #include <cmath> #include <algorithm> #include <vector> constexpr long long fibonacci(int num) { if (num <= 2) return 1; return fibonacci(num - 1) + fibonacci(num - 2); } int main() { auto start = clock(); long long num = fibonacci(70); auto duration = (clock() - start) / (CLOCKS_PER_SEC / 1000.); std::cout << num << "\n" <

问题 You know, like A = 1, B = 2 etc. I could just make a long list of if-thens, but maybe there's already a module for it. Bonus if it works like it does in "Excel Coordinates" where AA = 27 and continues. (Does this count as base26 numbers?) 回答1: def foo(c): return ord(c) - 64 foo('A') 1 foo('B') 2 off the top of my head :p 回答2: from string import ascii_uppercase letterKey = dict(list(zip( ascii_uppercase, range(1, 27)))) And as for the excel cords: geExceltValue = lambda string: sum([26**i *

问题 For some reason I can not get my function to return a string... $password = crypt_password_input($password, ""); //Encrypt Password longer than 8 characters function crypt_password_input($inputPassword, $newPassword) { $passwordLength = strlen($inputPassword); if($passwordLength > 8){ $encryptString = substr($inputPassword, 0, 8); $inputPassword = substr($inputPassword, 8); $newPassword .= crypt($encryptString, "HIDDENSALT"); crypt_password_input($inputPassword, $newPassword); }else{

问题 I have 3 columns. First column has unique ID, second and third columns have string data and some NA data. I need to extract info from column 2 and put it in separate columns and do the same thing for column 3. I am building a function as follows, using for loops. I need to split the columns after the third letter. [For example in the V1 column below, I need to break AAAbbb as AAA and bbb and put them in separate columns. I know I can use substr to do this. I am new to R, please help. UID * V1