linux C學習筆記04--記憶體映射

標籤：

記憶體映射代碼，開啟一個檔案與映射到記憶體中，對記憶體和檔案的修改都會反映到檔案中來，反之亦然，先貼代碼，以後再完善：

 

/*************************************************************************    > File Name: memory_map.c    > Author: hailin.ma    > Mail: [email protected]     > Created Time: Thu 28 May 2015 08:20:50 AM CST ************************************************************************/#include<stdio.h>#include <sys/mman.h>#include <fcntl.h>#include <string.h>#define MEM_MAP_SIZE 1000int memory_map(){    char * pmap = NULL;    int fd;    char rdbuf[100] = "\0";    fd = open("memory.txt",O_RDWR|O_CREAT|O_TRUNC,0660);    if(fd == -1)    {        perror("open error");        return -1;    }    write(fd,"hello world!",MEM_MAP_SIZE);        //write data to file,the write size must as long as MEM_MAP_SIZE        pmap = mmap(NULL,MEM_MAP_SIZE,PROT_READ|PROT_WRITE,MAP_SHARED,fd,0);        //map memory with file    printf("the memory is: %s\n",pmap);    memset(pmap,‘a‘,MEM_MAP_SIZE);    memcpy(pmap,"this is memory map",18);        //try to chang any charactor in memory        lseek(fd,0,SEEK_SET);            //move fd pointer to begin section        memset(rdbuf,0,sizeof(rdbuf));    read(fd,rdbuf,100);                //read the context in file    printf("the file is: %s\n",rdbuf);    munmap(pmap,10);    close(fd);    return 0;}

 

main函數調用後運行：

linux C學習筆記04--記憶體映射