Hello all,
I have a question about iterators. I have a container of functors
that operate on an std::string. The functors go something like this:
class Functor {
std::string operator()(cons t std::string& s) {/*manipulate
string*/; return newString;}
};
Now, I want to call the functors on a string argument. I write
something like this:
std::vector<Fun ctorvec;
/*Omitted creation and push_back of a couple Functors */
std::vector<Fun ctor>::const_it erator it = vec.begin();
std::vector<Fun ctor>::const_it erator end = vec.end();
std::string arg("Test argument");
for(; it != end; it++)
std::cout << *it(arg) << "\n"; //Why doesn't this work?
Instead of using the de-reference operator '*', I have to write the
following:
it->operator()(arg );
Can some kind soul explain to me why this is? I prefer the cleaner
syntax of the first statement.
-tryptik 4 2233
On Mar 6, 3:20 pm, "tryp...@gmail. com" <tryp...@gmail. comwrote:
Hello all,
I have a question about iterators. I have a container of functors
that operate on an std::string. The functors go something like this:
class Functor {
std::string operator()(cons t std::string& s) {/*manipulate
string*/; return newString;}
};
Now, I want to call the functors on a string argument. I write
something like this:
std::vector<Fun ctorvec;
/*Omitted creation and push_back of a couple Functors */
std::vector<Fun ctor>::const_it erator it = vec.begin();
std::vector<Fun ctor>::const_it erator end = vec.end();
std::string arg("Test argument");
for(; it != end; it++)
std::cout << *it(arg) << "\n"; //Why doesn't this work?
Instead of using the de-reference operator '*', I have to write the
following:
it->operator()(arg );
Can some kind soul explain to me why this is? I prefer the cleaner
syntax of the first statement.
-tryptik
well that is a hard question to anser but i think it is wrong tr*****@gmail.c om wrote:
Hello all,
I have a question about iterators. I have a container of functors
that operate on an std::string. The functors go something like this:
class Functor {
std::string operator()(cons t std::string& s) {/*manipulate
string*/; return newString;}
Functors should be const
std::string operator()(cons t std::string& s) const
{
...
}
};
Now, I want to call the functors on a string argument. I write
something like this:
std::vector<Fun ctorvec;
/*Omitted creation and push_back of a couple Functors */
std::vector<Fun ctor>::const_it erator it = vec.begin();
std::vector<Fun ctor>::const_it erator end = vec.end();
std::string arg("Test argument");
for(; it != end; it++)
std::cout << *it(arg) << "\n"; //Why doesn't this work?
Instead of using the de-reference operator '*', I have to write the
following:
it->operator()(arg );
Can some kind soul explain to me why this is? I prefer the cleaner
syntax of the first statement.
-tryptik
Just a question of operator precedence I think, try this.
std::cout << (*it)(arg) << "\n";
john tr*****@gmail.c om wrote:
I have a question about iterators. I have a container of functors
that operate on an std::string. The functors go something like this:
class Functor {
std::string operator()(cons t std::string& s) {/*manipulate
string*/; return newString;}
};
Now, I want to call the functors on a string argument. I write
something like this:
std::vector<Fun ctorvec;
/*Omitted creation and push_back of a couple Functors */
std::vector<Fun ctor>::const_it erator it = vec.begin();
std::vector<Fun ctor>::const_it erator end = vec.end();
std::string arg("Test argument");
for(; it != end; it++)
std::cout << *it(arg) << "\n"; //Why doesn't this work?
What do you mean by "doesn't work"? Does it compile?
Instead of using the de-reference operator '*', I have to write the
following:
it->operator()(arg );
Can some kind soul explain to me why this is? I prefer the cleaner
syntax of the first statement.
Use
(*it)(arg);
And read your favourite C++ book again about the precedence of operators.
V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask
<tr*****@gmail. comwrote in message
news:11******** **************@ q40g2000cwq.goo glegroups.com.. .
Hello all,
I have a question about iterators. I have a container of functors
that operate on an std::string. The functors go something like this:
class Functor {
std::string operator()(cons t std::string& s) {/*manipulate
string*/; return newString;}
};
Now, I want to call the functors on a string argument. I write
something like this:
std::vector<Fun ctorvec;
/*Omitted creation and push_back of a couple Functors */
std::vector<Fun ctor>::const_it erator it = vec.begin();
std::vector<Fun ctor>::const_it erator end = vec.end();
std::string arg("Test argument");
for(; it != end; it++)
std::cout << *it(arg) << "\n"; //Why doesn't this work?
As stated by others, this is actually:
*(it(arg))
But what you really want is
(*it)(arg)
so you have to specify that.
I now always use (*it) when derefernecing iterators for any context.
>
Instead of using the de-reference operator '*', I have to write the
following:
it->operator()(arg );
Can some kind soul explain to me why this is? I prefer the cleaner
syntax of the first statement.
-tryptik This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics |
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