c++将读取的文件内容一次性输出于屏幕

我给你的代码只是映射简单例子：
而注释给啦一些我的思路。
其实对于你想要的这种效果，你还应该理解i/o编程
可以参考：blog.csdn.net/querdaizhi/article/details/7436722
若是你觉得还有问题我们继续交流！

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>
//#include "tlpi_hdr.h"
#define errExit(msg) (perror(msg),(exit(1)))
int main(int argc,char * argv[])
{
    char * addr;
    int fd;
    struct stat sb;
    if(argc !=2 ||strcmp(argv[1],"--help")==0)
        //usageErr("%s file\n",argv[0]);
        errExit("usage..");

    fd=open(argv[1],O_RDONLY);//Looks ,here your should change as 
    /*
     *while file[i].txt no finish
     *  fd=open(file[i].txt)
     *  mmap(......)
     *  done...
     */
    if(fd==-1)
        errExit("open");
    /*Obtain the size of the file and use it to specify the size of
      the mapping and the size of the buffer to be written */
     if(fstat(fd,&sb)==-1)
         errExit("fstat");
     addr=mmap(NULL,sb.st_size,PROT_READ,MAP_PRIVATE,fd,0);
     if(addr==MAP_FAILED)
         errExit("mmap");
     if(write(STDOUT_FILENO,addr,sb.st_size)!=sb.st_size)
         errExit("partial/failed write");
    exit(EXIT_SUCCESS);
}