Writing a function that can modify it's number of parameters at runtime using vectors?

[Protoman]

I have a function that calculates the mean of the some numbers; I want
it to calculate the vector size at runtime. Can you help me out here?
Here's the function:

const long double& mean(long long x)
{
vector<int> v(x);
for(int i= 1; i <=x; ++i)
{
v.push_back(i);
}
const long double ret=accumulate(v.begin(), v.end(), 0.0) / v.size();
return ret;
}

If you could help me out, that'd be great. Thanks!!!

 

[Victor Bazarov]

[..]

This is not a chat room. Post. Wait. Read replies. Do not
post many times with the same content. It annoys people.

 

[kevin.hall]

This is a much faster equivalent to what you wrote:

const long double& mean(long long x)
{
double y = x;
return y*(y+1)/2;
}

 

[Protoman]

OK, now how do I let it accept user input for the data; I'm trying to
make averages for inputs other than 1 to x. And sorry for the mutiple
posting.

 

[kevin.hall]

You're the same programmer(!?!?!?) that needs an infinite-precision
floating point class for NASA! Come on... any programmer with a little
bit of experience would know (a) limitations of C/C++ and (b) how to
program something reasonalbe like what you requested in this thread (c)
look for books or free libraries to help them on these subjects. I
will not do your homework / school project for you.