Question

i’m working on gcc ,
i’m wondering if this is possible:

I have a function (NOTmain but aLocalFn) and I declare a local variable in it. Then I pass this local argument as a thread argument. is it doable? or there is the chance (depending on what is run first) that the aLocalVar will be lost before threadFunction is run and the reference idxPtr will be pointing to senselessness??

int *threadFunction(void *idxPtr){
    int rec_idx=(int) *idxPtr;

    //work in the thread with this variabel rec_idx
}

int aLocalFn(){
   int aLocalVar=returnsRecordIndex();

   pthread_create(&thread_id,&attr_detached,threadFunction, &aLocalVar)!=0)
   return 0;
}   

thank you for your help

Answer 1

This code is incorrect. The function aLocalFn may return before the thread function starts executing. And so by the time the thread function reads the local variable, the scope of that variable may have ended.

What can confuse matters is that this code may very well appear to work, at least some of the time. However, it is incorrect and you should use heap allocated memory instead.