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Generator/Exponential: Difference between revisions
→{{header|C}}: Added a templated c++ class
(→{{header|C}}: Added a templated c++ class) |
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Line 414:
$ ./main
529, 576, 625, 676, 784, 841, 900, 961, 1024, 1089</pre>
=={{header|C++}}==
A templated solution.
<lang cpp>#include <iostream>
using namespace std;
template<class T>
class Generator
{
public:
virtual T operator()() = 0;
};
// Does nothing unspecialized
template<class T, T P>
class PowersGenerator: Generator<T> {};
// Specialize with other types, or provide a generic version of pow
template<int P>
class PowersGenerator<int, P>: Generator<int>
{
public:
int i;
PowersGenerator() { i = 1; }
virtual int operator()()
{
int o = 1;
for(int j = 0; j < P; ++j) o *= i;
++i;
return o;
}
};
// Only works with non-decreasing generators
template<class T, class G, class F>
class Filter: Generator<T>
{
public:
G gen;
F filter;
T lastG, lastF;
Filter() { lastG = gen(); lastF = filter(); }
virtual T operator()()
{
while(lastG >= lastF)
{
if(lastG == lastF)
lastG = gen();
lastF = filter();
}
T out = lastG;
lastG = gen();
return out;
}
};
int main()
{
Filter<int, PowersGenerator<int, 2>, PowersGenerator<int, 3>> gen;
for(int i = 0; i < 20; ++i)
gen();
for(int i = 20; i < 30; ++i)
cout << i << ": " << gen() << endl;
}</lang>
Output:
<pre>
20: 529
21: 576
22: 625
23: 676
24: 784
25: 841
26: 900
27: 961
28: 1024
29: 1089
</pre>
=={{header|D}}==
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