How to use read function to read from terminal input (stdin)?

Question

The main function will be in an infinite loop reading the numbers that the user puts in the terminal and storing them on a buffer. My problem is that I need to read from terminal using this function:

read(int fd, void *buf, size_t count);

How can the file descriptor point to the terminal?! (I hope I'm not saying some barbarity)

Thanks in advance!

EDIT: I already took your advice, but something is missing. This is a small program that I wrote to test:

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

int buffer[5], i=0, j;

int main(){
   for(j=0; j<5; j++) buffer[j] = 0;
   while(i<5){
     read(STDIN_FILENO, buffer, 8);
     printf("->%d\n", buffer[i]);
     i++;
   }
   return 0;
}

Outup:

1
->2609
2
->0
3
->0
4
->0
5
->0

Why this doesn't print the numbers that I inserted?

Answer 1

Your process has three file descriptors open since it has been spawned: STDIN_FILENO , STDOUT_FILENO , STDERR_FILENO (0, 1, 2 respectively). These macros are defined in unistd.h .
read(STDIN_FILENO, buff, bytes)

Answer 2

By default the program's standard input is on file descriptor 0.

If you really mean to read from the terminal, instead of standard input, you can open() /dev/tty .

Answer 3

stdin is fd 0 ,

stdout is fd 1 , and

stderr is fd 2 .

Answer 4

On POSIX you can use symbols like STDIN_FILENO to represents the input of your application. But beware that the standard input is not always the terminal, especially when you redirect input/output via the shell.