files + records in c

tommycahir

i am having trouble when i reading a record from a file the first record that is read is "garbage" then the rest are ok could someone tell me what going on and an idea on how to solve it...
tanx


struct vertexnode{

char SiteName[20];
int XCoord;
int YCoord;
struct vertexnode *nextvertex;
struct arcnode *nextarc;
};


void saveGraph(vertexnode *graph)
{
FILE *fp;

fp = fopen("graph.txt","wt");
while (graph!=NULL)
{
fwrite(&*graph,sizeof (*graph),1,fp);
graph=graph->nextvertex;
}
fclose(fp);

}

//*****************************************************************************

vertexnode *loadGraph(void)
{
FILE* fp;
vertexnode* ptr = NULL;
long curpos;


fp = fopen("graph.txt","rt");
curpos = ftell(fp);
fseek(fp, curpos, SEEK_SET);
fflush(fp);

while (!feof(fp))
{
vertexnode* newnode;
newnode = GetvertexNode();
newnode->nextvertex = NULL;
newnode->nextarc = NULL;
fread(&*newnode,sizeof (*ptr),1,fp);
newnode->nextvertex = ptr;
ptr = newnode;
newnode->SiteName;
newnode->XCoord;
newnode->YCoord;
}

fclose(fp);
return (ptr);
}

hussey

have a look at this threadhttp://www.boards.ie/vbulletin/showthread.php?s=&threadid=75924&highlight=struct, its in C++ , but can give you an idea of how to write/read structs from files

DeadBankClerk

[php]struct vertexnode
{
char SiteName[20];
int XCoord;
int YCoord;
struct vertexnode *nextvertex;
struct arcnode *nextarc;
};

void saveGraph(vertexnode *graph)
{
FILE *fp;

fp = fopen("graph.txt","wt");
while (graph!=NULL)
{
// fwrite(&*graph,sizeof (*graph),1,fp);
fwrite(graph, sizeof (vertexnode),1,fp); // BETTER
graph=graph->nextvertex;
}
fclose(fp);

}[/php]

tommycahir

sorry guys
still have the prob it seems to be trying to read the last node twice????