I have to use 'generate' function on vector to create 10 objects. I have class Point with constructor:
Point(){
this->x=rand()%100;
this->y=rand()%100;
};
Then I create a vector and use 'generate' function:
vector<Point> v (10);
generate (v.begin(), v.end(), Point());
When I compile it I receive this error:
Type 'Point' does not provide a call operator
I don't know why.
It looks like you want to fill the vector with default constructed instances of Point
.
Before coming to your actual issue, that call to std::generate
is unnecessary, as v
will already have 10 default constructed instances of Point
.
But if you really want to call it, std::generate
expects as Generator
a function object, ie an object with operator()
. Point
doesn't have one, and the compiler complains. Passing a lambda is a good idea, as they are such function objects:
std::generate(v.begin(), v.end(), []() {
return Point{};
});
The prototype for the generator function is described here . It must be a function that returns the next value to generate. You are passing a single default constructed instance of Point
. Perhaps you were trying to provide Point
's constructor as the generator function, but a constructor does not meet the requirement (it doesn't return anything), should never be called directly, and it's address can never be obtained (neither can you get a reference to one).
You must provide a separate function that simply returns points. The easiest way is to pass std::generate
a lambda function. You would do something like this :
std::vector<Point> v(10);
std::generate(v.begin(), v.end(), []() { return Point{}; });
However, note that the line std::vector<Point> v(10);
already creates 10 default constructed Point
objects. Since your randomization logic is in your default constructor, it's redundant to use std::generate
in this case.
you need a function that generates the Points
Point RandomPoint() { return Point(); }
int main(int argA, char** argV)
{
vector<Point> v(10);
generate(v.begin(), v.end(), RandomPoint);
return 0;
}
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