Format output with terminal columns in C

Question

I'm trying to format a list of files using Terminal columns size in C, using write. I'm trying to format the output to look like the following, Without using printf or other formatting functions.

This's what I'm getting

here's my code

#include <stdio.h>
#include <sys/ioctl.h>  /* ioctl, TIOCGWINSZ */
#include <err.h>    /* err */
#include <fcntl.h>  /* open */
#include <string.h>
#include <unistd.h>

size_t  ft_strlen(const char *s)
{
    size_t  i;

    i = 0;
    while (s[i])
        i++;
    return (i);
}

int get_cols()
{
    struct winsize ws;
    int fd;
    int cols;

    cols = 0;
    /* Open the controlling terminal. */
    fd = open("/dev/tty", O_RDWR);
    if (fd < 0)
        err(1, "/dev/tty");

    /* Get window size of terminal. */ 
    if (ioctl(fd, TIOCGWINSZ, &ws) < 0)
        err(1, "/dev/tty");
    close(fd);
    cols = ws.ws_col;
    return (cols);
}

void    print_item(const char *str, int num_sp)
{
    char sp = ' ';

    write(1, str, ft_strlen(str));
    while (num_sp--)
        write(1, &sp, 1);
}

int get_max_strlen(const char *list[])
{
    int len = 0;
    int i = 0;

    while (list[i])
    {
        if (ft_strlen(list[i]) > len)
            len = ft_strlen(list[i]);
        i++;
    }
    return (len);
}

void    print_list(const char *list[], int cols)
{
    int max_len = get_max_strlen(list);
    int i = 0;
    int curr_len;
    int tmp_cols = cols;

    while (list[i])
    {
        curr_len = ft_strlen(list[i]);
        if (curr_len < tmp_cols)
        {
            print_item(list[i], max_len - curr_len + 1); //+1 for space
            tmp_cols -= curr_len;
        }
        else
        {
            write(1, "\n", 1);
            tmp_cols = cols;
        }
        i++;
    }
}

int main()
{
    const char *list[] = 
    {
        "21sh", "21sh.fr.pdf", "author", "ft_auto_misc.o", "ft_auto_search.o",
        "ft_auto_utils.o", "ft_bck_i_search.o", "ft_cd.o", "ft_cmd_utils.o",
        "ft_commands.o", "ft_ctrl_c_signal_handler.o", "ft_ctrl_keyboard.o",
        "ft_ctrl_terminal.o", "ft_cut.o", "ft_echo.o", "ft_env.o", "ft_env_utils.o",
        "ft_execute.o", "ft_export.o", "ft_free.o", "ft_get_data.o", "ft_hash_table.o",
        "ft_hash_table_utils.o", "ft_here_doc.o", "ft_here_doc_utils.o", "ft_history.o",
        "ft_hist_utils.o", "ft_logical_op.o","ft_manage_buff.o", "ft_manage_hist.o", 
        "ft_manage_pipes.o", "ft_more_utils.o", "ft_parenthesis.o", "ft_parenthesis_utils.o",
        "ft_redirection.o", "ft_redirection_utils.o", "ft_signals.o", "ft_sub.o",
        "ft_term_utils.o", "ft_utils.o", "includes", "libft", "main.o", "Makefile",
        "nbproject", "README.md", "src", "TODO", 
        0
    };

    print_list(list, get_cols());
    return 0;
}

Gerhardh · Accepted Answer · 2016-12-30 13:15:09Z

2

Your loop to print the list should look like this:

while (list[i])
{
    curr_len = ft_strlen(list[i]);
    if (curr_len > tmp_cols)
    {
        write(1, "\n", 1);
        tmp_cols = cols;
    }

    // Always print the item. Do not skip it.
    print_item(list[i], max_len - curr_len + 1); //+1 for space
    tmp_cols -= maxlen+1;  <=== Not only curr_len
    i++;
}

For each line you skipped one item as you only printed a '\n' instead of the item. "ft_env_utils.o" is missing in your output. You forgot to reduce remaining columns count by the number of padding bytes.

This should fix the incorrect column width. If printing column by column instead of row by row is also desired some extra sorting will be needed.

answered Dec 30, 2016 at 13:15

Gerhardh

12.4k4 gold badges19 silver badges47 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Junius L Over a year ago

Thanks, somehow the last item prints extra spaces and I have changed \n to \r.

Gerhardh Over a year ago

Yes, you print padding spaces for every item including the last one. To avoid this you might add some parameter to print_item indicating if it is the last item in the list.

Junius L Over a year ago

OK, thanks I added write(1, "\r", 1); at the end of the loop to fix it.

Collectives™ on Stack Overflow

Format output with terminal columns in C

1 Answer 1

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related