C++ Tutorial/template/overload template function
Overload generic method and non-generic method
<source lang="cpp">#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;
}</source>
generic3.56 not genericGood
Using an overloaded function template
<source lang="cpp">#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;
}</source>
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
<source lang="cpp">#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;
}</source>
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
