[Country EMBED strategy] [085] [Shared memory communication]

Shared memory

Shared memory is one of the IPC mechanisms that allows two related processes to access the same memory, which is an efficient way to pass data.

A.c

#include <sys/types.h>#include<sys/ipc.h>#include<sys/shm.h>#include<stdio.h>#include<string.h>#defineSIZE 2048typedefstructsharemem{intFlag//Share Flag    CharData[size];//Sharing Data}sharemem;voidMain () {//Create shared Memory    intkey; intShmid; Key= Ftok ("./",0); Shmid= Shmget (Key,sizeof(SHAREMEM), ipc_creat); //Mapping Shared MemorySharemem *Sharemem; Sharemem= (Sharemem *) Shmat (Shmid, NULL,0); //set up shared memorySharemem->flag =0;  while(1){        //Judging shared flags         while(Sharemem->flag! =0); //Get user Input        CharBuffer[size];                Fgets (buffer, SIZE, stdin); //Write shared Memorystrncpy (sharemem->data, buffer, SIZE); Sharemem->flag =1; //determine whether to exit        if(STRNCMP (Buffer,"quit",4) ==0){             Break; }    }        //out of shared memorySHMDT ((Const void*) sharemem);}

B.c

#include <sys/types.h>#include<sys/ipc.h>#include<sys/shm.h>#include<stdio.h>#include<string.h>#defineSIZE 2048typedefstructsharemem{intFlag//Share Flag    CharData[size];//Sharing Data}sharemem;voidMain () {//Open Shared Memory    intkey; intShmid; Key= Ftok ("./",0); Shmid= Shmget (Key,sizeof(SHAREMEM), ipc_creat); //Mapping Shared MemorySharemem *Sharemem; Sharemem= (Sharemem *) Shmat (Shmid, NULL,0); //set up shared memorySharemem->flag =1;  while(1){        //Judging shared flags         while(Sharemem->flag! =1); //Read Shared memory        CharBuffer[size]; strncpy (buffer, Sharemem-data, SIZE); Sharemem->flag =0; //Show shared Memoryprintf"%s", buffer); //determine whether to exit        if(STRNCMP (Buffer,"quit",4) ==0){             Break; }    }        //out of shared memorySHMDT ((Const void*) sharemem); //Delete Shared memoryShmctl (Shmid, Ipc_rmid, NULL);}

[Country EMBED strategy] [085] [Shared memory communication]