Thread: How to calculate the program running took?

You can't do that in standard C to interrupt the waiting of input. You have to do that via OS/library - specific functions.

OK. That means you can't do it. The best you can do is tell the user after they entered a value that they took too long.

Find a book or something. It's in time.h.

Then look it up.

Get yourself a book, and a good reference (may even be a book).

Originally Posted by DaniiChris

So none of you know it...its ok...will be waiting for others and thanks for the advice I will look in books

Listen, kid. The regulars on this forum know a lot more now than you will probably ever learn if you don't drop this arrogant attitude that you're entitled to every little bit of information on this forum.

Do we look like human compilers or books to you? We're not. We were once learning this stuff just like you, whether in books on our own, or as students, or however else. Many times newbies seem to think they are entitled to our knowledge simply because they are newbies and we are slightly more experienced. Well, that's stupid. We fought to get where we're at, putting up with hours upon hour of studying and practice, and you should be willing to put up with the same work to get the same gains.

Don't get us wrong. We'd love to help out, but you're pathetically clueless. It's not your fault you don't know anything, but it's your fault if you are not willing to learn properly. You have to ask meaningful questions and not waste our time. Part of programming is about managing your resources effectively. You are not managing your usage of this forum or of your time effectively.

This is the year 2008, and you can get all kinds of books, references, tutorials, and whatever else free right from the Internet. You should be taking advantage of this instead of pestering us to teach you how to do things you are clearly not ready to learn. I'm serious about this.

If you're smart, you'll think about what I'm saying and give it some consideration. It's important and it seriously will make you a better programmer and better in general at handling yourself in other situations.

Here's some code I just wrote (yeah, I had time and I tough it was an interesting problem, so I gave it a try; I didn't look for non-blocking IO function but instead I went another way) who ask the user for a number, but will only wait 5 seconds:

Code:

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

#include <time.h>
#include <signal.h>
#include <assert.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>

const unsigned int MAX_TIME = 5;
enum
{
    OK = 0,
    TOO_SLOW
} result;

void sig_handler(int sig_num)
{
    if (sig_num == SIGCHLD)
    {
        result = OK;
    }

    else if (sig_num == SIGALRM)
    {
        result = TOO_SLOW;
    }
}

int main()
{
    pid_t chld_process;

    struct sigaction sa;

    int shm_id;
    void *data;

    assert((shm_id = shmget(IPC_PRIVATE, sizeof(int), 0600 | IPC_CREAT)) != -1);
    assert((data = shmat(shm_id, NULL, 0)) != (void*) -1);

    sa.sa_handler = sig_handler;
    sigemptyset(&sa.sa_mask);
    sa.sa_flags = 0;
    assert(sigaction(SIGALRM, &sa, NULL) != -1);
    assert(sigaction(SIGCHLD, &sa, NULL) != -1);

    printf("Enter a number: ");
    fflush(stdout);

    assert((chld_process = fork()) != -1);
    if (chld_process == 0)
    {
        scanf("&#37;d", (int*) data);
        shmdt(data);
        exit(EXIT_SUCCESS);
    }

    alarm(MAX_TIME);
    pause();
    alarm(0);

    if (result == OK)
    {
        printf("Thanks for %d\n", * (int*) data);
    }

    else
    {
        kill(chld_process, SIGINT);
        printf("\nToo slow... moron.\n");
    }

    shmdt(data);

    return 0;
}

Of course, as you can see, it will only compile on POSIX and mostly-POSIX compliant system. I use only the basic stuff: shared data segments, process creation and signal. You know, this kind of stuff. I didn't put any comments since it's like so easy to understand.

Well, if you're really that young, that's great that you want to get into C, and I seriously congratulate you on the effort. Nevertheless, I still recommend you find a good book or reference of some sort. You will be wasting much of your time if you rely on people on forums to teach you how to go about this.

There are a list of recommended C books here as well as many tutorials online that you can learn from. They do teach these things, you just have to know how to find these resources.

My post to you wasn't to discourage you from posting here or from asking questions or from learning C. The post was to encourage you to put more independent research into your own questions and learning. Learn to use google very often for these things. Find and follow a good tutorial (this website has a collection of simple tutorials). Many, many times, when writing a program, I forget some detail or I very often discover there is something I just simply don't know that I need to look up somehow. Most of what I need can be found through google, either directly or indirectly. This ability, though incredibly simple, should never be underestimated. Researching a topic is important.

And this is also very important: Programming is really about concepts, not syntax. As I said before, one such concept is about managing resources in order to problem-solve.

The issue with teaching you all of these things isn't so much the idea of explaining it as much as the idea of explaining everything behind it. We'd be here for quite awhile if I was to try to explain how to do time-based I/O because (assuming this is Windows you're working on) I would have to explain aspects of the Windows API, I/O in general, and how you put it all together. This would require you to already know C, and from what it sounds, you're still pretty new to it. If I even tried to explain all of this, it would result in you probably not understanding a thing I was saying and just simply frustrating you.

You have to start slowly, and focus on the concepts. The syntax and other details come with experience as you work on it all. You really need a book of some sort or tutorials to follow with and slowly build a good working knowledge of the language.

The fact you were able to read through my post and respond the way you did appears to be a point in your favor. I think you may do quite well in the future.