Re: filling vectors in the parameter list
benben wrote:
utab wrote:
Dear all,
I have a function to get some string arguments. The point is that the
number of these string arguments may vary. So
foo(std::vector<std::string> &vec);
But I want to be able to initialize this vector at run-time with
different number of arguments. for instance
foo("str1","str2") // 2 args
foo("str1","str2","str3") // 3 args
foo("str1","str2","str3","str4") // 4 args and so on
I could find the way to put these parameters into the vector. Or is
there a better way to do this kind of task.
Regards
There is a way to declare a function to take varying number of
arguments. However, the way it is done is spectacularly dangerous
because the compiler won't get the type information to protect you.
IMO it is easier to populate the vector first, then pass it to foo:
{
vector<string> v(3);
v.push_back("str1");
v.push_back("str2");
v.push_back("str3");
foo(v);
}
If you find this too verbose you can write a vector_filler<> class
template to fill a vector via an overloaded << operator (like streams do.)
A std::tr1::tuple can also be used as a variable argument list and -
unlike a vector - the arguments do not all have to be of the same type:
#include <tr1/tuple>
#include <string>
#include <iostream>
using std::tr1::tuple;
using std::tr1::make_tuple;
using std::tr1::tie;
using std::string;
void f( tuple< string, int, double> params)
{
string s;
int n;
double d;
// fills in s, n and d
tie( s, n, d) = params;
std::cout << "s: " << s << "\n";
std::cout << "n: " << n << "\n";
std::cout << "d: " << d << "\n";
}
int main()
{
tuple<string, int, double> args( "hello", 5, 2.3 );
f(args);
}
Program output:
s: hello
n: 5
d: 2.3
Greg