Program stops and does nothing for no reason [closed] - c

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Here is my code. It will take the info from the user fine, but it doesn't call prims! (it doesn't even print the statement before the call..). The issue is, this main() is simply copy-and-pasted from an attempt at this problem using kruskals instead of prims.. the main is unchanged, and it used to work fine, the only difference is prims() is now there. I can't see any reason why the program would just.. stop (and then does nothing. Blinking cursor nothing). What's going on?
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define MAX 50
typedef struct graph{
int vertices;
int edges;
int vertex[MAX];
int edge[MAX][4]; /*[i][0]=i (edge ref) [i][1]=vertex1 [i][2]=vertex2 [i][3]=weight*/
} Graph;
void prims(Graph graph);
int main () {
Graph* graph=malloc(sizeof *graph);
printf("Please enter the number of vertices in your graph: ");
scanf("%i", &graph->vertices);
printf("\nPlease enter the number of edges in your graph: ");
scanf("%i", &graph->edges);
for (int i=0; i<graph->edges; ++i) {
graph->edge[i][0]=i;
ensure_valid_input:
printf("\nPlease enter the vertices connected by edge %i, and its weight: ",i+1);
scanf("%i %i %i", &graph->edge[i][1], &graph->edge[i][2], &graph->edge[i][3]);
if (graph->edge[i][1]>graph->vertices || graph->edge[i][2]>graph->vertices || graph->edge[i][1] <= 0 || graph->edge[i][2] <= 0) {
printf("\nERROR: One of these vertices is invalid; ensure they are both in range 1 - %d\n", graph->vertices);
goto ensure_valid_input;
}
}
printf("Try to call the function?");
prims(*graph);
/*Print result to screen*/
/*Print result to file*/
return 0;
}
void prims(Graph graph){
printf("Function called...");
/*Initialise sets and test-values*/
int edges_ordered[graph.edges];
int used_vertices[graph.vertices];
int used_edges[graph.vertices-1];
int least_avail_edge;
int least_edge_reset;
int existing_entry;
int done=1;
int vertex_present;
for (int i=0; i<graph.vertices; ++i) {
if (i=0) {
used_vertices[i]=0;
}
else {
used_vertices[i]=-1;
}
}
/*Order the edges*/
for (int i=0; i<graph.edges; ++i) {
least_avail_edge = least_edge_reset;
existing_entry = 1;
for (int j=0; j<graph.edges; ++j) {
if (graph.edge[j][3]<=graph.edge[least_avail_edge][3]) {
for (int k=0; k<graph.edges; ++k) {
if (edges_ordered[k]==graph.edge[j][0]) {
existing_entry=0;
}
}
if (existing_entry==1) {
least_avail_edge=j;
}
}
}
edges_ordered[i]=least_avail_edge;
}
//Diagnotstic Print
for (int i=0; i<graph.edges; ++i) {
printf("\n%d) Edge %d, Weight %d\n)", i+1, edges_ordered[i]+1, graph.edge[i][3]);
}
/*Continually add next appropriate edge to tree until spanning*/
while (done!=0) {
/*Test to see if all vertices are in the tree yet*/
done=0;
for (int i=0; i<graph.vertices; ++i) {
vertex_present=1;
for (int j=0; j<graph.vertices; ++j) {
if (graph.vertex[i]==used_vertices[j]) {
vertex_present=0;
}
}
if (vertex_present==1) {
/*Vertex is missing from tree -- not done!*/
done=1;
break;
}
}
}
}

Answer 1

There are a lot of problems with this code, but I suspect the culprit is inside your prims() function:
if (i=0) {
I think you mean ==. You're setting i to zero each time through the loop, which causes the loop to never terminate, freezing your program.
Other problems are that least_edge_reset is uninitialized, the return value of malloc is not cast (depends on the C/C++ version and compiler settings whether you'll get an error or warning for this), and sizeof *graph is awkward. Also there's no protection against exceeding the maximum number of edges, etc. etc., but I'll stop there since it's not what you were asking about.
I suspect your print statement IS running, but since there is no \n, it is being buffered and not displayed on screen right away, and never gets displayed because prims() is stuck in an infinite loop.