I am initializing a map map<string,int> ex;
in C++. I could not find contains_key or similar function in stl,
hence I am just using ex[inputString]++;
The debugger shows the int to be initialized to zero correctly, is it a good assumption?
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A:
Yes, values that do not exist when accessed with operator[] are default-constructed. For numeric values, this is 0.
That said, you're looking for the count method:
bool hasElement = ex.count("element");
GMan
2010-02-27 06:49:54
thanks, good to know that it is initialized to zero, saves the if !exists then initialize kind of structure needed in python
2010-02-27 06:53:03
@akshayubhat C++'s `map[k]` and Python's `dict.setdefault(k[,d])` are similar in that a non-existent key will be set to a default, as C++'s `map.find(k)->second` and Python's `dict[k]` similar in that a non-existent key will give an error. The two languages just chose different options for which to be the "common" operation.
ephemient
2010-02-27 07:02:43