why passing argument by reference(&ref) in a template function shows error ? but works fine if arguments passed by pointer(*ptr) ?

Tarun Jha

in the below program it i have used both ways i.e. passed arguments by reference and pointers. 1. Arguments by reference:

#include
using namespace std;

template
void swap(T &x, T &y){
T temp = x;
x = y;
y = temp;
}

void fun(int m, int n, float a, float b){

cout << "m & n before swap: " << m << " " << n << endl;
swap(m, n);
cout << "m & n after swap: " << m << " " << n << endl;

cout << "i & j before swap: " << a << " " << b << endl;
swap(a, b);
cout << "i & j after swap: " << a << " " << b << endl;

}

int main(){
fun(100, 200, 11.22, 33.44);

return 0;

}

2. Arguments by pointers:

#include
using namespace std;

template
void swap(T *x, T *y){
T temp = x;
x = y;
y = temp;
}

void fun(int m, int n, float a, float b){

cout << "m & n before swap: " << m << " " << n << endl;
swap(m, n);
cout << "m & n after swap: " << m << " " << n << endl;

cout << "i & j before swap: " << a << " " << b << endl;
swap(a, b);
cout << "i & j after swap: " << a << " " << b << endl;

}

int main(){
fun(100, 200, 11.22, 33.44);

return 0;

}

also if i pass the arguments by reference but make it a constant then also i works, why ?

#include
using namespace std;

template
void swap(const T &x, const T &y){
T temp = x;
x = y;
y = temp;
}

void fun(int m, int n, float a, float b){

cout << "m & n before swap: " << m << " " << n << endl;
swap(m, n);
cout << "m & n after swap: " << m << " " << n << endl;

cout << "i & j before swap: " << a << " " << b << endl;
swap(a, b);
cout << "i & j after swap: " << a << " " << b << endl;

}

int main(){
fun(100, 200, 11.22, 33.44);

return 0;

}

Thank you.

CPallini

You have a name clash with std::swap. Try

#include using std::cout;
using std::endl;

template
void swap(T &x, T &y){
T temp = x;
x = y;
y = temp;
}

void fun(int m, int n, float a, float b){

cout << "m & n before swap: " << m << " " << n << endl;
swap(m, n);
cout << "m & n after swap: " << m << " " << n << endl;

cout << "i & j before swap: " << a << " " << b << endl;
swap(a, b);
cout << "i & j after swap: " << a << " " << b << endl;

}

int main()
{
fun(100, 200, 11.22, 33.44);
}

Tarun Jha

ohh... Thank you

CPallini

You are welcome.