why segment fault, Post: 302570613

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Top Forums Programming why segment fault, Post 302570613 by yanglei_fage on Thursday 3rd of November 2011 10:03:31 PM

11-03-2011

Registered User

why segment fault,

I always get segment fault, why? can sb help me and modify it, I have spend on much time on

Code:

#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>
#include <string.h>
#define MAX 10
pthread_t thread[2];

void *thread1()
{

    int *a[16];
    int i, n;


    for (i = 0; i < 16; i++)
    {

    n=(size_t) ((rand() * 256.0) / (RAND_MAX + 1.0)) + 1;
        a[i] = (int*)malloc(n);
    if (a[i]==NULL)
        {
            printf("Error allocating memory!");
            exit (1);
        }

       printf("malloc a[%d]\n",i);

    }

    for (i = 16; i > 0; i--)
    {

        n=(size_t) ((rand() * 256.0) / (RAND_MAX + 1.0)) + 1;
        printf("remalloc a[%d]\n",i-1);
        a[i - 1] = (int*)realloc(a[i - 1], n);
    if ( a[i - 1]==NULL)
        {
            printf("Error reallocating memory!");
            exit (1);
        }


    }
    for (i = 0; i < 16; i += 2 )
        free(a[i]);
        printf("free1 a[%d]\n",i);
    for (i = 16; i > 0; i -= 2)
        free(a[i - 1]);
        printf("free2 a[%d]\n",i-1);
        pthread_exit(NULL);
}


void thread_create(void)
{
        int temp,i;
        memset(&thread, 0, sizeof(thread));          //comment1
        /**/
       for (i = 2; i > 0; i--)
{
        if((temp = pthread_create(&thread[i], NULL, thread1, NULL)) != 0)       //comment2
                printf("thread create failed\n");
        else
                printf("thread create\n");
}
}

void thread_wait(void)
{
   int i;
   for (i = 2; i > 0; i--)
{
        if(thread[i] !=0) {                   //comment4
                pthread_join(thread[i],NULL);
                printf("1\n");
        }
}
}

int main()
{

        printf("\n");
        thread_create();
        printf("\n");
        thread_wait();

        return 0;
}

Last edited by yanglei_fage; 11-04-2011 at 12:04 AM..

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LEARN ABOUT DEBIAN

ticker

NAME(1) 						      General Commands Manual							   NAME(1)

NAME

       ticker - scroll messages across the screen

SYNOPSIS

       ticker [options] [message]

DESCRIPTION

       ticker  is  a  program  that  continually scrolls a given message across the screen.  There is also an interface to allow other programs to
       change the message.

KEYS

       +, [up arrow]
	      Increase scroll speed.

       -, [down arrw]
	      Decrease scroll speed.

       [space]
	      Pause. Press any key to unpause.

OPTIONS

       -h, --help
	      Show summary of options.

       -u, --upper
	      Scroll text on the top line of the screen. (Default)

       -l, --lower
	      Scroll text on the bottom line of the screen.

       -fcolor, --foreground=color
	      Use the specified color as the forground color of the text that is scrolled.  The colors that may be used are:
	       black	       gray
	       red	       brightred
	       green	       brightgreen
	       brown	       yellow
	       blue	       brightblue
	       magenta	       brightmagenta
	       cyan	       brightcyan
	       lightgray       white

       -bcolor, --background=color
	      Use the specified color as the background color of the text that is scrolled. On most terminals, the background color  can  only	be
	      one of the colors listed in the first column above.

       -dsecs, --delay=secs
	      Number  of  seconds  delay  between updates of the display. This controls how fast the text scrolls. You may use decimals to specify
	      faster scroll speeds.  The default delay is 1 second; I find 0.1 more pleasing.

       -snum, --sysv=num
	      Read messages to display from the sysv shared memory segment with an id of num. This is only for use by other programs that need	to
	      be able to change the text ticker displays.

       -Snum, --size=num
	      Size of the shared memory segment to read, when using shared memory communication with another program. Default is 80 characters.

       -csecs, --check=secs
	      Minimum time between checks of the shared memory segment for a new message.  Default is every second. It may in fact check consider-
	      ably less often, as it only checks for a new message once per time that the current message scrolls around the screen.

       message
	      The message to scroll. Required unless -s is used, in which case it is optional.

NOTES

       To use the other 23 or so lines of your screen for something useful while the ticker is running, you might want to use splitvt(1)

AUTHOR

       Joey Hess <joey@kitenet.net>

																	   NAME(1)