c - mmap and struct (incompatible type error struct to void *) -

i'm getting error:

error: incompatible types when assigning type ‘struct sharedmem’ type ‘void *’

when trying mmap struct sharedmemory. here's i'm trying do:

//struct each card typedef struct card{     char c[3]; //card     char s; //suit } card;  //struct player information typedef struct player{     int num;     char* nickname;     char* fifo_p;     struct card* hand; } player;  //struct sharedmemory typedef struct sharedmem{     unsigned int nplayers;     unsigned int dealer;     struct player *players;     unsigned int roundnumber;     unsigned int turn;     struct card *tablecards; } sharedmem; 

then have function does:

int createsharedmemory(char* shmname,int nplayers){      int shmfd;     char shmname[100]={'\0'};     char *ps;     ps=&shmname[0];     strcat(ps,"/");     strcat(ps,shmname); // name = /shmname     shmfd = shm_open(shmname,o_rdwr,0755);     if (shmfd<0){         if (errno==2){ //file or directory not exist (shared memory space not created, meaning it's first process, create shmspace)             shmfd = shm_open(shmname,o_creat|o_rdwr,0755);             if (shmfd<0){                 perror("failure in shm_open()");                 fprintf(stderr,"error: %d\n",errno);                 exit(exit_failure);                          }         } else {             perror("failure in shm_open()");             fprintf(stderr,"error: %d\n",errno);             exit(exit_failure);         }     }      struct sharedmem shm; //  shm.players=malloc(nplayers*sizeof(player)); //  shm.tablecards=malloc(nplayers*sizeof(card));     ftruncate(shmfd, sizeof(sharedmem)); 

error: shm = mmap(0,sizeof(sharedmem),prot_read|prot_write,map_shared,shmfd,0);

    return 0;  } 

can tell me i'm doing wrong? thought attributes players , tablecards had allocated tried malloc no cigar.

you want pointer struct sharedmem:

struct sharedmem *shmem = mmap(...); 

time fire docs of mmap().