Add a dot (.) automatically while typing in C

Question

I want to know is there some function similar to scanf that allows custom typing in c. What I'm trying to make is while user is typing wanted date , dot is added every few characters. When user wants to confirm his input , he should press enter, and that variable is saved somewhere.

Example : user is typing 11.04.2015.

When he typed 11 , dot is added on console. Same goes after 4 , and 2015.

Thank you so much for your answers. The platform is Windows

You need to catch stdin and display what you want take a look here http://stackoverflow.com/questions/421860/capture-characters-from-standard-input-without-waiting-for-enter-to-be-pressed — Ôrel, Apr 11 '15 at 15:08
How will an automatic dot work? If user is typing a date, how is program expected to know whether a `1` will be January or another digit typed as he wants `11` for November? Your example used a single `4` and there is no 2-digit day *or* month (depending on date sequence format) starting with a `4` so it is a poor example. — Weather Vane, Apr 11 '15 at 15:17
@WeatherVane You are right , I should change that. I keep date inside string (not best idea , but I just play around with code anyway). I though , after user writes 2 characters for day , characters is printed on screen and also is added inside buffer. Same would go for month . For year, dot would appear after 4 characters . — tijetof, Apr 11 '15 at 15:54
You might want to use [readline](http://www.gnu.org/software/readline/) or [ncurses](http://www.gnu.org/software/ncurses/) - at least on Linux. — Basile Starynkevitch, Apr 17 '15 at 12:27

Ôrel · Answer 1 · 2015-04-11T16:39:53.023

2

A quick solution, this handle date on format group of 3 block. This add a . after two int

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

int main()
{
    char ch;
    char input[16];
    char *p;
    int i = 0;
    int part = 0;
    memset(input, 0, sizeof(input));

    p = input;
    system("stty raw -echo");
    while(1)
    {
        ch = getchar();
        if(ch == '~'){//terminate or come out of raw mode on "~" pressed
            system("stty cooked sane");
            return 0;
        }
        if (ch >= '0' && ch <= '9') {
            *p++ = ch;
            if (i++ == 1) {
                if (part++ == 2) {
                    printf("\rdone: %s\n", input);
                    /* Finish your prog here*/
                    break;
                }
                *p++ = '.';
                i = 0;
            }
        } else if (ch == '.') {
            *p++ = ch;
            i = 0;
            part++;
        }
        printf("\r%s", input);
    }
    system("stty cooked sane");
    return 0;
}

edited Apr 11 '15 at 16:39

answered Apr 11 '15 at 15:36

Ôrel

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You have to add more intelligence to detect one digit month and day – Ôrel Apr 11 '15 at 15:37
1

`getchar()` does not return a value keystroke by keystroke, so you are unable to reply with the `.` prompts OP asked for. And why is the code sprinkled with incompatible system calls? What is `bzero`? What is `strings.h`? What is wrong with `char input[16] = {0};`? – Weather Vane Apr 11 '15 at 16:13
@WeatherVane you need to fill all input with `\0` or add one after each char you add. You can use `memset` instead of `bzero` and remove strings.h I don't get the problem with `getchar` and `.`. Answer updated with `memset` – Ôrel Apr 11 '15 at 16:37
First point `char input[16] = {0};` initialises the whole array to `0` without help from a non-standard library. Second point `getchar()` doesn't return until you press `` so you can't anticipate the digit sequence char-by-char and insert a `'.'` on the fly as OP seems to want. So you might as well input each field separately, prompting with the result so far with a trailing `'.'` without any fancy stuff. – Weather Vane Apr 11 '15 at 16:44
for me this works (have you try my code ?), when you set stty to raw mode you read without waiting enter press – Ôrel Apr 11 '15 at 16:50
Yes of course I tried it before commenting, after removing the system and library specific stuff that I don't have in Windows. Nothing happens until I press ``. The other stuff is OS specific. It's a grand shame that standard C library functions do not return the value of a single keystroke, so MSVC `conio` functions `kbhit()` and `getch()` are OS specific. – Weather Vane Apr 11 '15 at 16:51
Ok my bad, I only test on debian and it does the job. `ncurses` or `conio` can be use to deal with the need but it is not POSIX – Ôrel Apr 11 '15 at 17:07

score 0 · Answer 2 · answered Apr 17 '15 at 14:56

Intentional off-topic advice here: don't get in user's way. Implement a function that parses anything looking like date instead, but please, never auto-put dots nor otherwise auto-separate d/m/y fields. If you do any of that, user will be unable to copy-paste dates and enter shortcuts (e.g. 1.1.15) and in general will be angry of such incompetent ui designer. Second, doing it right (what about backspaces? Non-digits? Comma?Dots?) leads to completely idiotic code complexity. Unless you have that as a strict requirement, you're just spending your time annoying your clients.

If you HAVE TO, sorry for the noise!

This whole thing was curiosity.I just only wanted to see if this is possible inside Windows , because I started this as side project for practicing programming. This is works inside console , so I don't expect from user to have option for copy-pasting. (what about backspaces? Non-digits? Comma?Dots?) I had made separate function for checking user input , if it is correct. I only allowed user to enter dots. — tijetof, Apr 24 '15 at 08:10

Add a dot (.) automatically while typing in C

2 Answers2