0
Do you have any way of ordering a struct in the form:
struct cidadecoord
{
char cidade[90];
int coordx, coordy;
}cidades[N];
N is worth 30 in the case, and I would like to order x and y coordinates, to find out which cities were further east, west, north and south. I’m struggling because I don’t know how to order keeping the information of the name of the city of each coordinate.
3
If the idea is just to take the cities further north, south, east and west, can do so:
int indNorte = 0;
int indSul = 0;
int indLeste = 0;
int indOeste = 0;
for(int i = 0; i < N; i++)
{
if(cidades[indNorte].coordy < cidades[i].coordy) indNorte = i;
if(cidades[indSul ].coordy > cidades[i].coordy) indSul = i;
if(cidades[indLeste].coordx < cidades[i].coordx) indLeste = i;
if(cidades[indOeste].coordx > cidades[i].coordx) indOeste = i;
}
You need to go through all the points necessarily. Sorting through multiple layers will be worse. Here you already get the index of cities without having to order everything.
I would need to create other structs to indNorte, indSul, indLeste and indOthis or that way you did it is already enough?
It depends.. if you’re going to use it to display cities, you can directly use this index to pick up by name.. Example, city name further north will be cidades[indNorte].cidade. If you are going to return from a function, you can do a struct or something similar (like an array of indices, each representing more to the north, south, east and west). Going to taste.
Got it! Thank you
1
Uses the function qsort() of the standard library with its own sorting function
int orderbyx(const void *a, const void *b) {
const struct cidadecoord *aa = a;
const struct cidadecoord *bb = b;
return aa->coordx - bb->coordx;
}
int orderbyy(const void *a, const void *b) {
const struct cidadecoord *aa = a;
const struct cidadecoord *bb = b;
return aa->coordy - bb->coordy;
}
/* ... */
qsort(cidades, N, sizeof *cidades, orderbyx);
/* cidades[0] tem a cidade com x menor */
/* cidades[N-1] tem a cidade com x maior */
/* ... */
qsort(cidades, N, sizeof *cidades, orderbyy);
/* cidades[0] tem a cidade com y menor */
/* cidades[N-1] tem a cidade com y maior */
Browser other questions tagged c classification struct array
You are not signed in. Login or sign up in order to post.
Everything depends on the order of your ordering. How do you want to order? In which priority? First x, then y? A distance, ie sqrt(x 2 + y 2), and then the name? Or the name comes first?
– rodrigogq
@rodrigogq In case, I would need to sort x and y separately. The values of x ordered would give me the city farthest west (the lowest value of x) farther east (the highest value of x) and with the values of y ordered I would know the city farther north and farther south, likewise.
– emic
Do you need to order or just find this information? If it is not necessary to order !
– rodrigogq
@I thought about ordering, because I thought it would be easier to find the highest and lowest value.
– emic