Can I declare a map like this
map<string, vector<string>> mymap;
I thought it is applicable.
However, it shows not.
I tried
map<string, vector<string>*> mymap;
and then it is OK
What's the rule of this?
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131answers:
2
+17
A:
You need an extra space:
map<string, vector<string> > mymap;
^ see the extra space
Without the extra space, the >> gets parsed as the right shift operator.
The rules have been modified in C++0x, making the extra space unnecessary. Some compilers (e.g., Visual C++ 2008 and above) already do not require the extra space.
James McNellis
2010-06-06 19:33:57
g++ gives this nice error: `'>>' should be '> >' within a nested template argument list`
anon
2010-06-06 19:44:21
Actually, it's `std::map<std::string, std::vector<std::string> >`, but I realize I'm on a lost crusade here.
sbi
2010-06-06 20:42:58
@sbi : while we're being pedantic, how do you know it's `std::`? Maybe he wrote his own. Or maybe he has `using namespace std;` or even `using std::string;` and `using std::map;` ;) Out of curiosity, why 'crusade' for the qualification?
Stephen
2010-06-06 23:01:34
@Stephen: Someone who fails at the famous (and, admittedly, embarrassing) `>>` of nested templates will not have written their own C++ container matching those of the std lib. (And God help us if they had.) As for `using namespace std`, see [this answer](http://stackoverflow.com/questions/2879555/2880136#2880136).
sbi
2010-06-06 23:09:58
@sbi : Yes, I was just giving you a hard time ;) Thanks for the link, the arguments are good.
Stephen
2010-06-06 23:22:07