CODEWITHSUNDEEP
cpthreads
Aishwarya Radhakrishnan
Aishwarya Radhakrishnan

Reputation: 159

incompatible pointer types passing 'void (void *) to parameter of type 'void *

I have created pthread as follows:

void function1(void *s) {
start = (*(int *)s ;
}

pthread_t threads[numthreads];
int ids[numthreads];
for (i = 0; i < numthreads; i++) {
    ids[i] = i;
    int * p = &ids[i] ;
    pthread_create(&threads[i], NULL, function1, (void *)p);
}

But this is giving me error:

>> mpicc -o hprogram hprogram.c
warning: incompatible pointer types passing 'void (void *)' to
      parameter of type 'void * _Nullable (* _Nonnull)(void * _Nullable)'
      [-Wincompatible-pointer-types]
                        pthread_create(&threads[i], NULL, function1, (void *)...
                                                          ^~~~~~~~~~
/usr/include/pthread.h:328:31: note: passing argument to parameter here
                void * _Nullable (* _Nonnull)(void * _Nullable),
                                            ^
1 warning generated.

This is an mpi program and im creating a hybrid mpi using pthreads.

Upvotes: 2

Views: 5226

Answers (1)

Remy Lebeau
Remy Lebeau

Reputation: 595961

pthread_create() expects a pointer to a function that takes a void* as input and returns a void* as output, but your function returns a void instead. You just need to add a * to the return type, and add a return statement, eg:

void* function1(void *s) {
    start = *(int *)s;
    return NULL; // <-- or whatever you want
}

Upvotes: 6

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