Chandrashekar wrote:
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> Hi all,
>
> I am using "vectors" and also Borland C++ compiler for fist time. I
> wrote the following code.
>
> /************************************************** *********/
> #include<stdio.h>
> #include<iostream.h>[/color]
<iostream.h> is a non-standard header. Use <iostream> instead, and
<stdio.h> is deprecated and should be replaced by <cstdio>. But it
doesn't seem that you use anything from that header anyway.
[color=blue]
> #include <vector>
> #include <algorithm>
> #include <numeric>
>
> class Moving_Average{
> private: // Moving_Average class will contain the vector forecast
>
> vector<double> forecast;[/color]
vector is in namespace std. So write:
std::vector<double> forecast;
[color=blue]
> public:
>
> void Moving_Average(int size)
> {
> forecast.reserve(size); //I am specifying the size of vector
> here
> }
>
> void calculate(double *da, int time){
> /* This function will calculate the moving averages (one method of
> forecasting)
> and then store the values in the vector
> */
> double sum=0;
> for(int i=1;i<=time;i++) {
> sum+=*(da+i);[/color]
That's not an error, but it would look cleaner if you wrote:
sum+=da[i];
I wonder: does da really point to time+1 values, and why aren't you
using the first value? Remember, indexes start at 0.
[color=blue]
> }
> cout<<"sum of the first tge "<<sum<<endl;[/color]
cout and endl are also in namespace std.
[color=blue]
> forecast.pushback(sum/time);
>
> for(int i=time+1;i<=size;i++) {[/color]
Where is size defined?
[color=blue]
>[/color]
forecast.pushback(forecast[time+i-1]+((*(da+time+i-1)-*(da+i-1))/time));[color=blue]
> }
> for(int i=1;i<=forecast.size();i++) {
> cout<<"moving average for period "<<i<<" -->
> "<<forecast[i]<<endl;
> }
> }
> };
>
>
> void main()[/color]
main() must return int in C++. Some compilers let you get away with it,
but it's still an error.
[color=blue]
> {
> Moving_Average MA;[/color]
Here you create a Moving_Average object using the default constructor.
Unfortunately, that class doesn't have a default constructor, so you
can't do that.
[color=blue]
> cout<<"Enter the no.of periods of historic data"<<endl;
> cin>>periods;
> MA(periods);[/color]
Is that supposed to construct the MA object? You can't do that. This
will instead try to call operator() of the Moving_Average class. Since
there is no operator() defined, this can't work. You cannot construct
an object twice. Either defer the construction to this place, i.e.
remove the first line of main() and write here:
Moving_Average MA(periods);
or create an own member function to specify the size. Anyway,
reserve()ing the space in a vector is only an optimization. It's not
mandatory. If you don't do that, push_back() will automatically
allocate the needed space.
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> vector<double>data(periods); // This vector holds the data
>
> for(int i=1;i<=periods;i++) {
> cout<<"Enter data for period --> "<<i<<" ";
> cin>>data[i];[/color]
Here, you have the index problem again (and at various other places).
You don't put anything in the first element of the vector and you write
one element past its end.
[color=blue]
> }
> MA.calculate(data.begin(),2);[/color]
Why 2? Shouldn't it be periods? Also, you can't specify data.begin()
here. This function returns an iterator to the first element of the
vector. While a vector iterator can be a pointer, it's not required to,
and some compilers (like gcc) have an own iterator class. Use &data[0]
instead.
[color=blue]
>
> }
>
> /******************************************* /
>
> I am getting following erros.
>
> 1)VECTOR.h(984,2) Cannot create pre-compiled header:code in header
> 2)tria.cpp(9,14):Type name expected
> 3)tria.cpp(9,14):Declaration missing;
>
> and so on..[/color]
You should have listed all of them and marked the lines your compiler is
referring to. It makes it a lot easier to find the errors.
[color=blue]
>
> Pls mail me what is wrong with my code.[/color]
No. This is not a write-only newsgroup. Post here - read here.
