Can anyone describe the following declaration?
template<> float func<float>(char *txt)
{
blah blah
}
What is the second <> for?
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2 Answers
The template<> means that this function is a template specialization. The second <float> means that this is the specialization for float.
For example:
#include <iostream>
template <class T> void somefunc(T arg) {
std::cout << "Normal template called\n";
}
template<> void somefunc<float>(float arg) {
std::cout << "Template specialization called\n";
}
int main(int argc, char *argv[]) {
somefunc(1); // prints out "Normal template called"
somefunc(1.0f); // prints out "Template specialization called"
return 0;
}
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This is a specialized template function. It happens when you try to specialized a generic template function. Usually you will have another deceleration as
template<typename T> float func(char *txt) {
T vars[1024];
blah blah
}
It happens sometime you want to do a specialized declaration for certain type T. In previous example, if T is bool type, you might want to change the behavior of vars array to save some space (because each bool entry might still take 32bits).
template<> float func<bool>(char *txt) {
int vars[32];
blah blah
}
By defining a specialized version, you are allowed to manipulate the vars array in bit-wise manner.
Comments
