pvz333

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/mman.h>

#define panic(syscall)          \
   do {                         \
       perror(syscall);         \
       return EXIT_FAILURE;     \
   } while (0)

int main(int argc, char * argv[])
{
    int fd;
    int status;
    struct stat st;
    int i, intvar;
    int file_size;
    char *memory;
 intvar = atoi(argv[2]);

    fd = open(argv[1], O_RDONLY);
    if (fd < 0)
        panic("open");

    status = fstat(fd, &st);
    if (status < 0)
        panic("fstat");
    file_size = st.st_size;


    memory = mmap(NULL, file_size, PROT_READ, MAP_PRIVATE, fd, 0);
    if (memory == MAP_FAILED)
        panic("mmap");


    for (i = 0; i < file_size; i++)
    if (intvar -1 == i){
        printf("%c", memory[i]);
        printf( "%\n");
    }
    munmap(memory, file_size);
    close(fd);
    return 0;
}