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plurals

POpthread_t pointer as argument of pthread_create
primarykey
Id
13956285
data
AcceptedAnswerId
13956335
AnswerCount
3
ClosedDate
CommentCount
1
CommunityOwnedDate
CreationDate
2012-12-19T16:00:48.510
FavoriteCount
0
LastActivityDate
2016-12-15T12:35:45.657
LastEditDate
2016-08-11T03:37:41.963
LastEditorUserId
454322
OwnerUserId
454322
ParentId
0
PostTypeId
1
Score
2
ViewCount
17421
LastEditorDisplayName
text
Body
The first argument of pthread_create is a pthread_t pointer. In the hello program below, if the first argument is a pointer to pthread_t (<code>pthread_t*</code>) instead of a pthread_t (<code>pthread_t</code>) the program ends with <code>Segmentation fault</code>...why? I don't remember seeing <code>pthread_t*</code> as the declared type of the first argument of <code>pthread_create</code>. And chapter 2 of Butenhof's book Programming with POSIX Threads says: <blockquote> To create a thread, you must declare a variable of type <code>pthread_t</code> [not <code>pthread_t*</code>]. </blockquote> But <a href="http://pubs.opengroup.org/onlinepubs/7908799/xsh/pthread_create.html" rel="nofollow">according to the specification</a> the first argument of <code>pthread_create</code> is a pointer to <code>pthread_t</code>, so why the segmentation fault? <hr> Segmentation fault <pre><code>pthread_t* thr; pthread_create(thr, NULL, &hello, NULL); </code></pre> <hr> Runs OK <pre><code>pthread_t thr; pthread_t* pntr = &thr; pthread_create(pntr, NULL, &hello, NULL); </code></pre> <hr> hello program: <pre class="lang-c prettyprint-override"><code>#include <pthread.h> #include <stdio.h> void * hello(void *arg){ printf("Hello\n"); pthread_exit(NULL); } int main(int argc, char **argv){ pthread_t thr = 1; pthread_create(&thr, NULL, &hello, NULL); pthread_join(thr, NULL); return 0; } </code></pre> <hr> pthread_create prototype: <pre><code>int pthread_create(pthread_t *thread, const pthread_attr_t *attr, void *(*start_routine)(void*), void *arg); </code></pre>
Tags
<c><pointers><pthreads>
Title
pthread_t pointer as argument of pthread_create
singulars
PostAcceptedAnswerId
1. PO
 singulars
 PostTypePostTypeId
 PTAnswer
PostParentId
1. This table or related slice is empty.
PostTypePostTypeId
1. PTQuestion
UserLastEditorUserId
1. USuser454322
UserOwnerUserId
1. USuser454322
plurals
PostLinksPostIdRelatedPostId
1. PL
 singulars
 LinkTypeLinkTypeId
 LTLinked
PostLinksRelatedPostIdPostId
1. This table or related slice is empty.
PostsAcceptedAnswerId
1. This table or related slice is empty.
PostsParentIdCreationDate
1. PO
 singulars
 PostTypePostTypeId
 PTAnswer
2. PO
 singulars
 PostTypePostTypeId
 PTAnswer
VotesPostIdCreationDate
1. VO
 singulars
 PostPostId
 POpthread_t pointer as argument of pthread_create
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
2. VO
 singulars
 PostPostId
 POpthread_t pointer as argument of pthread_create
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
CommentsPostId
1. COSee the difference between _defined_ and _declared_ in http://stackoverflow.com/questions/1433204/what-are-extern-variables-in-c
 singulars
 PostPostId
 POpthread_t pointer as argument of pthread_create
 UserUserId
 USuser454322

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