Passing parameter to pthread
- by Andrei Ciobanu
Hello, i have the following code:
#include <stdlib.h>
#include <stdio.h>
#include <pthread.h>
#define NUM_THREADS 100
struct thread_param {
char *f1;
char *f2;
int x;
};
void *thread_function(void *arg){
printf("%d\n", ((struct thread_param*)arg)->x);
}
int main(int argc, char *argvs[]){
int i, thread_cr_res = 0;
pthread_t *threads;
threads = malloc(100 * sizeof(*threads));
if(threads == NULL){
fprintf(stderr,"MALLOC THREADS ERROR");
return (-1);
}
for(i = 0; i < NUM_THREADS; i++){
struct thread_param *tp;
if((tp = malloc(sizeof(*tp))) == NULL){
fprintf(stderr,"MALLOC THREAD_PARAM ERROR");
return (-1);
}
tp->f1 = "f1";
tp->f2 = "f2";
tp->x = i;
thread_cr_res = pthread_create(&threads[i],
NULL,
thread_function,
(void*)tp);
if(thread_cr_res != 0){
fprintf(stderr,"THREAD CREATE ERROR");
return (-1);
}
}
return (0);
}
What i want to achieve, is to print all the numbers from 0 to 99, from threads. Also i am experimenting a way to pass a structure as a thread input parameter.
What i am finding curios, is that not all the numbers are shown, eg:
./a.out | grep 9
9
19
29
39
49
And sometimes some numbers are shown twice:
...
75
74
89
77
78
79
91
91
Can you please explain me why is this happening ?
No errors are shown.
