MPI第四站 （2）-- linux上 学习从接收信息中拿出来更多的信息 - 接收前就得到信息的一些count状态

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main.cpp

#include "iostream"
#include "mpi.h"
#include "stdlib.h"
using namespace std;


void check_before_rece(){
    MPI_Init(NULL, NULL);
    int world_size;
    MPI_Comm_size(MPI_COMM_WORLD, &world_size);
    if(world_size != 2){
        cout << "proesses must be equals to 2"<<endl;
        MPI_Abort(MPI_COMM_WORLD, 1);
    }
    int world_rank;
    MPI_Comm_rank(MPI_COMM_WORLD, &world_rank);

    int number_amount;
    if(world_rank == 0){
        const int MAX_NUMBERS = 100;
        int numbers[MAX_NUMBERS];
        //设置下随机数
        srand(22);
        //从MAX_NUMBERS范围中，找到一个整数
        number_amount = (rand()/(float)RAND_MAX) * MAX_NUMBERS;

        //发送
        MPI_Send(numbers, number_amount, MPI_INT, 1, 88, MPI_COMM_WORLD);
        cout<<"0 sent "<<number_amount <<" numbers to 1 "<<endl;
    }else if(world_rank == 1){
        MPI_Status status;
        //定义一个邮件，来接收收到的信息
        MPI_Probe(0, 88, MPI_COMM_WORLD, &status);
        // 从接收的信息里拿到一些信息，比如接收数据的count等
        MPI_Get_count(&status, MPI_INT, &number_amount);
        // 申请一个大小为number_amount的数组，用来存储申请到的数据
        int *number_buf = new int[number_amount];
        MPI_Recv(number_buf, number_amount, MPI_INT, 0, 88, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
        cout << "1 received "<<number_amount << " numbers from 0.Message source = " <<status.MPI_SOURCE <<" tag = "<<status.MPI_TAG;
        //
        delete [] number_buf;
    }
    MPI_Finalize();

}

int main() {
    // 尝试动态接收信息
//    get_status();

    // 在接收前，先拿到信息的count数目，然后动态分配内存
    check_before_rece();
}

mpic++ main.cpp -o main.out

mpirun -np 2 ./main.out