Get the variable value from a previous struct in arrays of structs - c

Question

I have the following struct:
struct V {
int d;
int tip;
char naziv[10];
int veza;
int tezina;
};
typedef struct V Vertex;
The following declaration:
void kreiranje(Vertex cvorovi[]);
The following main function:
int main(){
int n=15;
Vertex cvorovi[n];
Vertex *pokazivac = &cvorovi[n];
kreiranje(pokazivac);
}
And this is the code behind the kreiranje function:
void kreiranje(Vertex cvorovi[])
{
int x,y,d,f,g;
int i = 0;
int brojac = 0;
char z[10];
char line[50];
char lined[50];
FILE *fr;
FILE *fp;
fr = fopen ("nodes.txt", "rt");
fp = fopen ("edges.txt", "rt");
while(fgets(line, 50, fr) != NULL)
{
sscanf (line, "%d|%d %s", &x, &y, &z);
cvorovi[n].d = x;
cvorovi[n].tip = y;
strcpy(cvorovi[n].naziv, z);
if(brojac < n){
fgets(lined, 50, fp) != NULL;
sscanf (lined, "%d-%d,%d", &d, &f, &g);
if (cvorovi[n-1].d == d){
printf ("\n Cvor prosli je %d\n", cvorovi[n-1].d);
printf ("\n %d \n", d);
cvorovi[n].veza = y;
cvorovi[n].tezina = g;
}
else {
cvorovi[n].veza = y;
cvorovi[n].tezina = g;
}
}
brojac++;
}
fclose(fr);
fclose(fp);
}
The files are like this:
edges.txt
1-2,4
1-3,5
nodes.txt
1|1 EL_01
2|2 TF_01
In the first line of nodes.txt, first number presents the ID, that is used in edges.txt. My problem is the following - how can I check and assign if the ID has more than one of the connections that are given in the edges.txt (just like the example shows)?
The file values read okay, however I am not sure how can I get the previous member's of the struct values to use with comparison.

Answer 1

My problem is the following - how can I check and assign if the ID has more than one of the connections that are given in the edges.txt (just like the example shows)?
There are several ways to represent a graph in programs. I think in your case the easiest would be Adjacency Matrix or Incidence Matrix:
int AdjacencyMatrix[n][n];
somewhere in main():
memset(AdjacencyMatrix, 0, sizeof(AdjacencyMatrix));
In your reader function (kreiranje):
fgets(lined, 50, fp) != NULL;
sscanf (lined, "%d-%d,%d", &d, &f, &g);
int From=d;
int To=f;
AdjacencyMatrix[From][To]=1
AdjacencyMatrix[To][From]=1; <<- Only if this is undirected graph
then,
if you want to check node's X connections, use this:
for(i=0;i<n;++i) {
if(AdjacencyMatrix[X][i]==1) {
printf("Node %d links to %d\n", X, i);
}
}

Answer 2

You appear to want something a bit more like this:
/* ... data type and function declarations ... */
#define MAX_VERTICES 15
int main() {
Vertex cvorovi[MAX_VERTICES];
int n;
/* arguments are a pointer to the array _start_, plus its size: */
/* the number of vertices actually read is returned */
n = kreiranje(cvorovi, MAX_VERTICES);
/* ... */
return 0;
}
and
int kreiranje(Vertex cvorovi[], int n) {
int brojac = 0;
/* ... other local variable declarations ... */
while ((brojac < n) && (fgets(line, 50, fr) != NULL)) {
/* ... loop body ... */
brojac++;
}
return brojac;
}
I suggest having function kreiranje() return the number of vertices actually read, as shown, because you will need to know that to do anything further with them.
As to checking for multiple connections attributed to the same ID, you keep track of what you've read so far, and you read until you've seen enough to be confident that reading more is unnecessary. I know that's very abstract, but the details depend on the assumptions you can make about the form and organization of your data, and on the data structures you use in your program. If you're asking about a general approach to your problem rather than about details of how to implement it, then your question is probably inappropriate for SO.