What does the STL map[key] return if the key wasn’t a initialized key in the map? [duplicate]

A default constructed std::string ins inserted into the std::map with key ‘b’ and a reference to that is returned. It is often useful to consult the documentation, which defines the behavior of operator[] as: Returns a reference to the object that is associated with a particular key. If the map does not already contain such … Read more

TypedDict when keys have invalid names

According to PEP 589 you can use alternative syntax to create a TypedDict as follows: Movie = TypedDict(‘Movie’, {‘name’: str, ‘year’: int}) So, in your case, you could write: from typing import TypedDict RandomAlphabet = TypedDict(‘RandomAlphabet’, {‘A(2)’: str}) or for the second example: RandomAlphabet = TypedDict(‘RandomAlphabet’, {‘return’: str}) PEP 589 warns, though: This syntax doesn’t … Read more

Is it possible to store functions in a dictionary?

It sounds like you probably want something like: Dictionary<string, Func<string[], int>> functions = …; This is assuming the function returns an int (you haven’t specified). So you’d call it like this: int result = functions[name](parameters); Or to validate the name: Func<string[], int> function; if (functions.TryGetValue(name, out function)) { int result = function(parameters); … } else … Read more

c# dictionary How to add multiple values for single key?

Update: check for existence using TryGetValue to do only one lookup in the case where you have the list: List<int> list; if (!dictionary.TryGetValue(“foo”, out list)) { list = new List<int>(); dictionary.Add(“foo”, list); } list.Add(2); Original: Check for existence and add once, then key into the dictionary to get the list and add to the list … Read more

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