in normally we should add key
and value
together in dictionary type
. like:
myDict.Add(key1, value1); myDict.Add(key2, value2);
I want to know, Is there any way to add key
first, then insert its value
? (not both of them at the same time)
Add an item only when the key does not exist in dict in Python (setdefault()) In Python, you can add a new item to the dictionary dict with dict_object[key] = new_value . In this way, if the key already exists, the value is updated (overwritten) with the new value.
Yes, sets : set() -> new empty set object set(iterable) -> new set object Build an unordered collection of unique elements. Related: How is set() implemented? Show activity on this post.
If the value type of the dictionary is nullable, you could add a null value: myDict. Add(key1, null); If the value is non nullable, you can use a default value, either default or some out of range value, depending on your expected meaningful values.
Dictionaries can't have null keys.
If the value
type of the dictionary is nullable, you could add a null value:
myDict.Add(key1, null);
If the value
is non nullable, you can use a default value, either default
or some out of range value, depending on your expected meaningful values.
myDict.Add(key1, default(int)); myDict.Add(key1, Int32.MinValue);
as mentioned in the comments, there is no discernible merit in doing this. You can add values at any time, there is no need to pre-initialize a dictionary with keys.
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