c++ script help

[zerobinary]

#include <algorithm>
#include <iomanip>
#include <ios>
#include <iostream>
#include <string>
#include <vector>
using namespace std;
int main ()
{
cout <<" plz enter your first name: ";
string name;
cin>>name;
cout<<"Hello, "<<name<<"!"<<endl;
cout<<plz enter ur midterm and final exam grades: ";
double midterm, final;
cin>>midterm>>final;
cout<<"enter all ur homeworks grades, :
"followed by end-of-file: ";
vector<double> homework;
double x;
while (cin>>x)
homework.push_back(x);
typedef vector<double>::size_type vec_sz;
vec_sz size= homework.size();
if(size==0) {
cout<<endl<<"u must enter ur grades. "
"plz try again."<<endl;
return1; // does that mean if this statement fail it restart the if statement or the whole app
sort(homework.begin(), homework.end() );
vec_sz mid=size/2
double median;
median=size %2 ==0 ? (homework[mid]+homework[mid-1] /2
:homework[mid];
//isn't homework[mid]= to homework homework[size/2] which is how many numbers are contain in homework
//just how does it works don't very get it
streamsize prec=cout.precison(3)
<<0.2+midterm+0.4 *final+0.4*median//isn't median =size%2
<<setprecison(prec)< <end;
return0;
}
 

I have read the book seven times, but still don't get it.
I know it sounds fishy, but I very need ur help.
Ur voice are super important to me.
Plz lend me a hand

[Studlyami]

What problems are you having? are you getting an error message.? A little more information please.

[zerobinary]

no i just don't understand the script. Plz help
#
return1; // does that mean if this statement fail it restart the if statement
line 28
line 32-34
#
median=size %2 ==0 ? (homework[mid]+homework[mid-1] /2
#
:homework[mid];
#
//isn't homework[mid]= to homework homework[size/2] which is how many numbers
and line 37
<<0.2+midterm+0 .4 *final+0.4*medi an//isn't median =size%2

[kreagan]

no i just don't understand the script. Plz help
return1; // does that mean if this statement fail it restart the if statement

no no. I means that if no homeworks were inputed, stop the program. The return will break out of main. Basically shutting down your program.

median=size %2 ==0 ? (homework[mid]+homework[mid-1] /2
:homework[mid];

To take the median, you need to find the middle test. However, if there is an even number of tests, which one is the middle. Here's a visual example:

1 2 3 4 5 < the median is 3
1 2 3 4 < the median is (2 + 3)/2

This checks the size, if the size is even, do first command (between question mark and colon), if not, do what is after the colon. Basically it is a boolean if statement.

Hope that helped.

[zerobinary]

median=size %2 ==0 ? (homework[mid]+homework[mid-1] /2
:homework[mid];
sorry i still don't get it.
I get the non-pc version how to compute median.
Like if it is even divide the size /2
for example
10/2
the median will be 5 number +6 number /2
And the odd number is size/2
then the number to that is the median.
But the problem is isn't
median=size %2 ==0 ? (homework[mid]+homework[mid-1] /2
:homework[mid];
only calculate where is the median located ,but not the median itself???????

[Studlyami]

wow i must be slow 2 replies before i finished.

median will equal the value located in the homework vector
or it will equal the average of the two middle values in the homework vector.

[zerobinary]

Err don't quite get what do u mean by that.
Sorry about that.

[Studlyami]

okay

homework is a vector that contains doubles
if (size % 2 == 0) //there are an even number of grades
median = (homework[mid] + homework[mid-1] / 2) // (double + double) / 2
else // there are an odd number of grades
median = homework[mid] //equals the double value located in the middle of the vector

[JosAH]

Maybe it's because it's Sunday overhere but I find this thread very chaotic.
Suppose the homework[] array is sorted in ascendng or descending order. Let the
number of elements in that homework[] array be 'n'.

There are just two cases:

1) n is odd; the median is homework[n/2];
2) n is even; the median is (homework[n/2]+homework[n/2+1])/2;

if n&1 == 1 then n is an odd number; there's not much more to it.

kind regards,

Jos

[zerobinary]

o so because size is vector double
Which means it actually contain the number itself and not how many numbers there is right???
It is Sunday, I know I am sorry for bugging u in Sunday.