CODEWITHSUNDEEP
cstdin
Tudor Ciotlos
Tudor Ciotlos

Reputation: 1845

How do I read from stdin a text and write it to a file using low level file processing?

I tried using the following code to read a text from the keyboard and write it into the file text.dat. The file was created but it was empty.

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <io.h>
#include <string.h>

int main()
{
    char s[201];
    int n,f = open("text.dat", O_RDWR | O_CREAT);
    while (fgets(s,200,stdin) != NULL)
        write(f, s,sizeof(s));
    close(f);
    return 0;
}

Upvotes: 0

Views: 1571

Answers (3)

dziam
dziam

Reputation: 1

You are opening file in wrong way. Try open("text.dat", O_RDWR | O_CREAT,0666 );

P.S.
You simply don't have write access to file.

Upvotes: 0

egrunin
egrunin

Reputation: 25053

The write is wrong. Try this:

write(f, s, sizeof(s));

The second parameter should be a pointer to the beginning of s. What you're actually passing is a pointer to the pointer.

While you're at it, get rid of that unused int n:

int f = open("text.dat", O_RDWR | O_CREAT);

Edited to add

Your write() must use strlen() instead of sizeof() - you're probably writing out uninitialized junk, which makes it appear that the file is empty.

write(f, s, strlen(s));

Upvotes: 0

aragaer
aragaer

Reputation: 17848

write(f, s, strlen(s)) Though I'd use read() instead of fgets() and used its result instead of strlen()

Upvotes: 1

Related Questions