How do we create multiple thread during runtime in C programming language? If we need to create same amount of thread as specified by the user how do we do it?
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Possible dup: stackoverflow.com/q/4964142/132382pilcrow– pilcrow2012-06-10 04:26:09 +00:00Commented Jun 10, 2012 at 4:26
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4 Answers
On Linux use pthreads
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
void *print_message_function( void *ptr );
int main(int argc, char *argv[])
{
pthread_t thread1, thread2;
char *message1 = "Thread 1";
char *message2 = "Thread 2";
int iret1, iret2;
/* Create independent threads each of which will execute function */
iret1 = pthread_create( &thread1, NULL, print_message_function, (void*) message1);
iret2 = pthread_create( &thread2, NULL, print_message_function, (void*) message2);
/* Wait till threads are complete before main continues. Unless we */
/* wait we run the risk of executing an exit which will terminate */
/* the process and all threads before the threads have completed. */
pthread_join( thread1, NULL);
pthread_join( thread2, NULL);
printf("Thread 1 returns: %d\n",iret1);
printf("Thread 2 returns: %d\n",iret2);
exit(0);
}
void *print_message_function( void *ptr )
{
char *message;
message = (char *) ptr;
printf("%s \n", message);
}
3 Comments
falstro
I seems your
print_message_function is missing a return statement?
Tom
Seems so, but it only issues a warning in gcc
That's because of a technicality in the standard which requires the implementation to attempt to compile and run the program. (Not all implementations follow this requirement, but gcc does exactly follow what the standard says, in this case.) This has to do with not requiring complex control-flow analysis, especially with functions that may not return (e.g. abort(), exit(), terminate(), ...). However, the code is wrong and should definitely be fixed.
Check _beginthread for Windows and posix threads for linux
Comments
#include<stdio.h>
#include<pthread.h>
#include<unistd.h>
#include<stdlib.h>
void *print()
{
printf("\nThread Created");
}
int main()
{
int ch,i;
pthread_t *t;
printf("Enter the number of threads you want to create : ");
scanf("%d",&ch);
t=(pthread_t *)malloc(ch * sizeof(pthread_t ));
for(i=0;i<ch;i++)
{
pthread_create(&t[i],NULL,print,NULL); //Default Attributes
}
for(i=0;i<ch;i++)
{
pthread_join(t[i],NULL);
}
}
This is the most basic code for creating threads during runtime in Linux OS using pthread library.
