Function that calculates the arithmetic mean using vectors?

[Protoman]

I have a function that calculates the mean of the some numbers; I need
it to accept any number of parameters (one needs to be the number of
the other parameters) 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;
}

I want it to calculate the vector size at runtime. If you could help me
out, that'd be great. Thanks!!!

[Victor Bazarov]

Protoman wrote:

I have a function that calculates the mean of the some numbers; I need
it to accept any number of parameters (one needs to be the number of
the other parameters) Can you help me out here?
You need to see an implementation of 'fprintf'. va_args and va_list
are the macros to be used. Search the web for an example of how to
use them.
[..]

V

[Protoman]

I want to use vectors though.

[Victor Bazarov]

Protoman wrote:

I have a function that calculates the mean of the some numbers; I need
it to accept any number of parameters (one needs to be the number of
the other parameters) Can you help me out here? [..]

'va_start', 'va_end', and 'va_list' are the macros you should read
about. The web is your friend.

[Karl Heinz Buchegger]

Protoman wrote:

I want to use vectors though.

Pass the vector to the function.
Handling user input surely is not the responsibility
of a function which calculates a mean.

long double mean( vector< int > values )
{
// now calculate the mean of the passed
// vector and return it
}

One function - one responsibility

--
Karl Heinz Buchegger
kb******@gascad .at

[Protoman]

Here's my rewritten program(it finally works!!!!):

#include <iostream>
#include <cstdlib>
#include <vector>
#include <numeric>
using namespace std;

long double mean(vector<lon g double>& v)
{
long double ret=(accumulate (v.begin(),v.en d(), 0.0)/v.size());
return ret;
}
int main()
{
for(;;)
{
cout << "Enter the number of items: " << endl;
int num;
cin >> num;
vector<long double> v;
for(int i=0;i<num;++i)
{
cout << "Enter a number: ";
long double temp;
cin >> temp;
v.push_back(tem p);
}
long double ret=mean(v);
cout << "Here's the mean: " << fixed << ret << endl;
}
system("PAUSE") ;
return 0;
}

Now, how would I rewrite to make it more efficient and modularized; I'd
like some ideas. Thanks for the help!!!

[Karl Heinz Buchegger]

Protoman wrote:

Here's my rewritten program(it finally works!!!!):

#include <iostream>
#include <cstdlib>
#include <vector>
#include <numeric>
using namespace std;

long double mean(vector<lon g double>& v)
{
long double ret=(accumulate (v.begin(),v.en d(), 0.0)/v.size());
return ret;
}

int main()
{
for(;;)
{
cout << "Enter the number of items: " << endl;
int num;
cin >> num;
vector<long double> v;
for(int i=0;i<num;++i)
{
cout << "Enter a number: ";
long double temp;
cin >> temp;
v.push_back(tem p);
}
long double ret=mean(v);
cout << "Here's the mean: " << fixed << ret << endl;
}
system("PAUSE") ;
return 0;
}

I don't see, how the outermost for loop is ever terminated.
How about: If the user enters 0 for the number of items, the program
terminates.

<sidenote>
Did you format your code in that way or did that happen during the posting.
If you formatted that code, then work on your formatting style. The above
is awefull to read. If that formatting happend during posting, get a better
newsreader. If your programs get longer, no one here will be willing to wade
through such unformatted text
</sidenote>
Now, how would I rewrite to make it more efficient and modularized; I'd
like some ideas. Thanks for the help!!!

Eg. move the whole input thing into a function of its own.
You might also want to try the following: When the program asks
for a number, enter 'a' and see what happens. I am trying to push you
into the direction of having a function which does just the task of entering
a number, but it does so with handling all possible errors and probably retrying
the input, until a valid input has been received.

Glad to see that you switched your attitude and we can talk normal with each
other. I am pretty sure that with that attitude you made it into some killfiles
and it will take some time to get out of there. You want all the help you can get,
so beeing in other peoples killfile isn't something you want to be.

--
Karl Heinz Buchegger
kb******@gascad .at

[Protoman]

OK, here we go, inputting's a seperate function now:

#include <iostream>
#include <cstdlib>
#include <vector>
#include <numeric>
using namespace std;
void input(vector<lo ng double>& v)
{
cout << "Enter the number of items: " << endl;
int num;
cin >> num;
for(int i=0;i<num;++i)
{
cout << "Enter a number: ";
long double temp;
cin >> temp;
v.push_back(tem p);
}
}

long double mean(vector<lon g double>& v)
{
input(v);
long double ret=(accumulate (v.begin(),v.en d(), 0.0)/v.size());
return ret;
}

int main()
{
vector<long double> v;
for(;;)
{
long double ret=mean(v);
cout << "Here's the mean: " << fixed << ret << endl;
bool cont;
cout << "Continue?[1=yes|0=no]: " << endl;
cin >> cont;
if(cont==true)c ontinue;else break;
}
system("PAUSE") ;
return 0;
}

Next time I'll just post snips of my code. Now how to I do the error
checking? Thanks for the help!!!

[Protoman]

Oh, and I think there's a function in cstdlib that terminates the
program; could you tell me what that function is?

[John Harrison]

Protoman wrote:

Oh, and I think there's a function in cstdlib that terminates the
program; could you tell me what that function is?

exit and abort both do that (in different ways).

john