Thread: Writing Data Randomly to a Random-Access File

just trying to run and understand this example from the book. the code compiles and runs correctly but i get weird results in the file. the account number i enter appears as a symbol in file, and the double value i enter appears something like this in the file - ÌÌÌ£#¹ü‡t @. and records are placed randomly (i guess that's the result of random access file?). why is all of these?

Code:

struct clientData {	int account;
	char firstName[10];
	char lastName[15];
	double balance;
};


int main() {


	struct clientData client = {0, "", "", 0.0};
	FILE *ptF;


	if ((ptF = fopen("credit.txt", "rb+"))==NULL) {
		printf("File could not be opened.\n");
	} else {
		printf("Enter account 1 to 100, 0 to end:\n? ");
		scanf("%d", &client.account);
		while (client.account != 0) {
			printf("Enter first, last name, balance: ");
			fscanf(stdin, "%s%s%lf", client.firstName,
				client.lastName, &client.balance);
			fseek(ptF, (client.account - 1)*sizeof(struct clientData), SEEK_SET);
			fwrite(&client, sizeof(struct clientData), 1, ptF);
			printf( "Enter account number\n? " );
			scanf("%d", &client.account);
		}
		fclose(ptF);
	}
	getch();
	return 0;
}

How are you trying to view the file? You wrote the file in binary mode with the write() function so you can't view the file with a normal editor, you need to use something like a hex editor.

Jim

okay i did that. is this how it should look like?



i tried to read these data from file with another code and it printed the correct account number and balance, as i inputted (and not weird symbols), i understand that the weird symbols were because the file was being written in binary mode. and how can i view the file in a plain text format?

how can i view the file in a plain text format?

You can't. A binary file is not meant to be read like a text file. If you want a text format then you should open the file in "text" mode and use the formatted output methods like fprintf(). But remember you will give up random access, because a text file is considered a sequential file.



Jim