C++ Tutorial/template/overload template function — различия между версиями
Admin (обсуждение | вклад) м (1 версия: Импорт контента...) |
|
(нет различий)
| |
Текущая версия на 10:30, 25 мая 2010
Overload generic method and non-generic method
#include<iostream.h>
#include<string.h>
template<class T>
T min(T a,T b)
{
cout << "generic";
return (a<b?a:b);
}
char *min(char *a,char *b)
{
cout << "not generic";
return (strcmp(a,b)<0?a:b);
}
int main()
{
double a=3.56,b=8.23;
char s1[]="Hello",s2[]="Good";
cout<<min(a,b)<<endl;
cout<<min(s1,s2)<<endl;
}generic3.56 not genericGood
Using an overloaded function template
#include <iostream>
using std::cout;
using std::endl;
template<class T> T larger(T a, T b);
long* larger(long* a, long* b);
template <class T> T larger (const T array[], int count); // Overloaded templat
e prototype
int main() {
cout << "Larger of 1.5 and 2.5 is " << larger(1.5, 2.5) << endl;
cout << "Larger of 3.5 and 4.5 is " << larger(3.5, 4.5) << endl;
int a_int = 35;
int b_int = 45;
cout << larger(a_int, b_int)<< endl;
long a_long = 9;
long b_long = 8;
cout << larger(a_long, b_long)<< endl;
cout << *larger(&a_long,&b_long)<< endl;
double x[] = { 10.5, 12.5, 2.5, 13.5, 5.5 };
cout << larger(x, sizeof x/sizeof x[0]) << endl;
return 0;
}
template <class T> T larger(T a, T b) {
cout << "standard version " << endl;
return a>b ? a : b;
}
long* larger(long* a, long* b) {
cout << "overloaded version for long* " << endl;
return *a>*b ? a : b;
}
template <class T> T larger (const T array[], int count) {
cout << "template overload version for arrays " << endl;
T result = array[0];
for(int i = 1 ; i < count ; i++)
if(array[i] > result)
result = array[i];
return result;
}standard version Larger of 1.5 and 2.5 is 2.5 standard version Larger of 3.5 and 4.5 is 4.5 standard version 45 standard version 9 overloaded version for long* 9 template overload version for arrays 13.5
Using function template specialization
#include <iostream>
using std::cout;
using std::endl;
template<class T> T larger(T a, T b); // Function template prototyp
e
template<> long* larger<long*>(long* a, long* b); // Specialization
int main() {
cout << "Larger of 1.5 and 2.5 is " << larger(1.5, 2.5) << endl;
cout << "Larger of 3.5 and 4.5 is " << larger(3.5, 4.5) << endl;
int a_int = 35;
int b_int = 45;
cout << larger(a_int, b_int)<< endl;
long a_long = 9;
long b_long = 8;
cout << larger(a_long, b_long)<< endl;
cout << *larger(&a_long,&b_long)<< endl;
return 0;
}
template <class T> T larger(T a, T b) {
cout << "standard version " << endl;
return a>b ? a : b;
}
template <> long* larger<long*>(long* a, long* b) {
cout << "specialized version " << endl;
return *a>*b ? a : b;
}standard version Larger of 1.5 and 2.5 is 2.5 standard version Larger of 3.5 and 4.5 is 4.5 standard version 45 standard version 9 specialized version 9
