Iam trying to make selection sort for array of objects considering i have Data class
I want to sort them depending on the id attribute of the object
class Data
{
public:
string name;
int id;
};
}
int main()
{
Data m[3];
m[0].id = 5;
m[1].id = 4;
m[2].id = 8;
selsort(m, 3);
cout << m[0].id;
};
I cannot understand what is wrong nothing happens to the array ?
Change:
if ((mry[min].id < mry[j].id) < 0)
to:
if ((mry[min].id > mry[j].id) )
You are finding the minimum index, so you have to swap if you find an index with a value that is lesser than the current minimum.
A better way to accomplish this is to make your function take in another parameter called a comparator function which tells the function how to compare; that way you can reuse your function if you change to mind and what to sort it by another parameter.
void selsort(Data mry[], int n, std::function<int(Data, Data)> cmp) // mry[] is the object array, n is the
// number of objects in the array
{
int pass, j, min;
Data temp;
for (pass = 0; pass <= n - 2; pass++) // passes
{
min = pass;
for (j = pass + 1; j < n; j++) // in each pass
if (cmp(mry[min], mry[j]) > 0)
min = j;
temp = mry[min];
mry[min] = mry[pass];
mry[pass] = temp;
}
}
And you can define a compare by id function:
int compare_by_id(Data d1, Data d2)
{
return d1.id - d2.id;
}
Call your function like this:
selsort(array, size, compare_by_id);
The best part is you can define your own function that can compare the elements as you want and that way your selsort() is versatile.
It seems there is a typo in the function declaration
void selsort(media mry[], int n)
^^^^^
I think you mean
void selsort( Data mry[], int n)
^^^^
This if statement
if ((mry[min].id < mry[j].id) < 0)
does not make sense.
You should write
if ( mry[min].id < mry[j].id )
Or if you want to sort in the ascending order then write the condition like
if ( mry[j].id < mry[min].id )
coutresult is 5