в 14:21, 25 мая 2010

2010-05-25T14:21:17Z

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2010-05-25T10:30:06Z

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==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>
<pre class=codeResult>generic3.56
not genericGood</pre>

==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>
<pre class=codeResult>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</pre>

==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>
<pre class=codeResult>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</pre>

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в 14:21, 25 мая 2010

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