when i running the following program, i have this error (Exception non gérée à 0x00B54BE2 (mpich2nemesis.dll) dans samedi1.exe : 0xC0000005 : Violation d'accès lors de la lecture de l'emplacement 0x00000000.)

program :

#include <stdio.h>

#include "mpi.h"

int main(int argc, char *argv[])

{

int a[8] = { 1, 2, 3, 4, 5, 6, 7, 8 };

int rcounts[4] = { 2, 2, 2, 2 };

int disp[4] = { 0, 2, 4, 6 };

int b[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };

int procid;

MPI_Init(&argc, &argv);

MPI_Comm_rank(MPI_COMM_WORLD, &procid);

MPI_Scatterv(&a, rcounts, 0, MPI_INT, &b, 100, MPI_INT, 0, MPI_COMM_WORLD);

printf("%d", b[0]);

printf("sanaa");

MPI_Finalize();

return 0;

}