nested struct , fread ,fwrite

i haf my nested struct ready ... i'm trying to add a new thing into my data base that is books loan.. there fore i haf a main struct which shows the name and info all tat and nested struct in the main for the books.. well my problem is how do i write into the same file as the main struct ? and read from the file...

is this correct
eg.fwrite(&info.book.sizeof info.book,clfile); << For writing the nested struct into the file ?

It helps if you try to form whole words and complete sentences. For example:

"Hi, I have created a file, which has a given structure in it. I've modified the structure, and want to rewrite the original file, with the new structure. How can I do this?"

Now, I have to assume that's what you meant. See how much clearer it was when I stated it? At any rate, here's what you do:

Code:

struct oldstruct
{
    ...stuff...
};
struct newstruct
{
    ...stuff + new stuff...
};

open file for reading
open another for writing
while not at the end of the input file
    read into an instance of old structure
    assign old data members across to the new structure instance
    fill the other "new stuff" portion of said instance
    write new structure to output file
close both files
remove old file (the one you just used for input)
rename new file (the one you just used for output)

Quzah.

i dun really get it ... heres where i'm stuck at

Code:

struct loan {
	char bookid[6], bookname[20], datedue[9],dateloan[9];
}com;

struct cus_info {
	int id;
	char name[40];
	struct loan;
}cus;

void loan(void)
{
FILE *cusfile,*temp;
int idd;

temp=fopen("c:\\temp.dat","a");
	if((cusfile=fopen("c:\\cus.dat","r+")) == NULL)
			{
				gotoxy(17,5);
				printf("Database Is Empty!");
				getch();
			}
	else
	{
		gotoxy(17,5);
		printf("Enter '0' To Return To Main Menu");
		gotoxy(17,7);
		printf("Enter ID : ");
		scanf("%d",&idd);
		if(id == 0)
		{
		return;
		}
		while(!feof(cusfile))
		{
				fread(&cus,sizeof cus,1,cusfile);
			if(feof(cusfile))
				break;
					if(id != cus.cus_id)
				fwrite(&cus,sizeof cus,1,temp);

Code:

struct loan {
	char bookid[6], bookname[20], datedue[9],dateloan[9];
}com;

struct cus_info {
	int id;
	char name[40];
	struct loan book; /* or whatever you like to call it */
}cus;

Magicz68, there are a few things wrong with your code besides the crucial error viaxd pointed out (you have to name the struct inside the struct). Why do you only check the return value of fopen() for one file, not both? You also need to check the return value of scanf() if you are going to use it. You shouldn't use feof() to control a loop either, read here: http://faq.cprogramming.com/cgi-bin/...&id=1043284351