This question already has answers here: How do I merge two dictionaries in a single expression (take union of dictionaries)? (48 answers) Closed 9 years ago. How do you calculate the union of two dict objects in Python, where a (key, value) pair is present in the result iff key is in either dict (unless … Read more
What is the most idiomatic way to do the following? def xstr(s): if s is None: return ” else: return s s = xstr(a) + xstr(b) update: I’m incorporating Tryptich’s suggestion to use str(s), which makes this routine work for other types besides strings. I’m awfully impressed by Vinay Sajip’s lambda suggestion, but I want … Read more
I’m just wondering should I use std::size_t for loops and stuff instead of int? For instance: #include <cstdint> int main() { for (std::size_t i = 0; i < 10; ++i) { // std::size_t OK here? Or should I use, say, unsigned int instead? } } In general, what is the best practice regarding when to … Read more
I’d like to know the best way (more compact and “pythonic” way) to do a special treatment for the last element in a for loop. There is a piece of code that should be called only between elements, being suppressed in the last one. Here is how I currently do it: for i, data in … Read more
I am trying to reverse an int array in Java. This method does not reverse the array. for(int i = 0; i < validData.length; i++) { int temp = validData[i]; validData[i] = validData[validData.length – i – 1]; validData[validData.length – i – 1] = temp; } What is wrong with it? 47 Answers 47 To reverse … Read more
How can I loop through a std::map in C++? My map is defined as: std::map< std::string, std::map<std::string, std::string> > For example, the above container holds data like this: m[“name1”][“value1”] = “data1”; m[“name1”][“value2”] = “data2”; m[“name2”][“value1”] = “data1”; m[“name2”][“value2”] = “data2”; m[“name3”][“value1”] = “data1”; m[“name3”][“value2”] = “data2”; How can I loop through this map and access … Read more
There’s this one thing in C++ which has been making me feel uncomfortable for quite a long time, because I honestly don’t know how to do it, even though it sounds simple: How do I implement Factory Method in C++ correctly? Goal: to make it possible to allow the client to instantiate some object using … Read more
I’m calling a bunch of methods that return a list. The list may be empty. If the list is non-empty, I want to return the first item; otherwise, I want to return None. This code works: def main(): my_list = get_list() if len(my_list) > 0: return my_list[0] return None but it seems to me that … Read more
If I have a Python dictionary, how do I get the key to the entry which contains the minimum value? I was thinking about something to do with the min() function… Given the input: {320:1, 321:0, 322:3} It would return 321. 16 Answers 16
How would you initialise a static Map in Java? Method one: static initialiser Method two: instance initialiser (anonymous subclass) or some other method? What are the pros and cons of each? Here is an example illustrating the two methods: import java.util.HashMap; import java.util.Map; public class Test { private static final Map<Integer, String> myMap = new … Read more
