My C shell code is not working, could someone please fix it. It is supposed to r

Question

My C shell code is not working, could someone please fix it.

It is supposed to read from a file 300 char and then write it to a different file, and do it as a loop (read another 300 char) until everything

is read and have been written into the other file.

I am using Linux shell, so if you fix it in another OS hopefully it will work for me too, but it needs checking, thanks.

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

int main()
{
int fd1, fd2;
char c [301];
int r, w;
fd1 = open("/etc/passwd", O_RDONLY);
if (fd1 < 0) {
        return -1;
}

fd2 = open("lab7taskoutput.txt", O_WRONLY | O_CREAT | O_TRUNC, 0644);
if (fd2 < 0) {
        printf("Unable to open out3.txt");
        exit(1);
}

while(r > 0) {
    r = read(fd1, c, 300);
    w = write(fd2, c, r);
}

}

Explanation / Answer

Following is the program. I have used generic names that can be easily modified to the file name that you require.

=====================================================================================

Please provide your feedback if you find the solution helpful

===========================================

#include <stdio.h>
#include <stdlib.h>

#include <fcntl.h>

int main()
{
    FILE *fd1, *fd2;
    char file[100], c;

    printf("Enter the filename to open for reading ");
    scanf("%s", file);

    // Open one file for reading
    fd1 = fopen(file, "r");
    if (fd1 == NULL)
    {
        printf("Unable to open %s ", file);
        exit(0);
    }

    printf("Enter the filename to open for writing ");
    scanf("%s", file);

    // Open another file for writing
    fd2 = fopen(file, "w");
    if (fd2 == NULL)
    {
        printf("Cannot open file %s ", file);
        exit(0);
    }

    // Read contents from file
    c = fgetc(fd1);
    while (c != EOF)
    {
        fputc(c, fd2);
        c = fgetc(fd1);
    }

    printf(" Contents copied to %s", file);

    fclose(fd1);
    fclose(fd2);
    return 0;
}

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