Write System Call

Question

I am writing this program in LINUX

#include <fcntl.h>
int main()
{

    int rd,id;
    char buff[10]={0};

    id = open("p_child.c",O_RDONLY|O_APPEND|O_WRONLY);
    if(id>1)
    {
        printf("I am file descriptor %d \n",id);

        rd = read(id,buff,8);
        printf("I am Reading file %s",buff);

        write(1,"New\n",4);
        printf("\nI am Writing file %s \n",buff);

    }
}

Its output is like printing 'New' before READ System Call. Why is this Happening?? As Write System call is used after "printf" of Read System call.

Answer 1

这是因为输出一直缓冲到您写出换行符为止。

Answer 2

更新此行将起作用

printf("I am Reading file %s \n",buff);

Answer 3

You forgot to add "\\n" in printf before write system call.

rd = read(id,buff,8);
printf("I am Reading file %s\n",buff);
write(1,"New\n",4);