1#include <stdio.h>
2#include <stdlib.h>
3
4int
5main (int argc, char *argv[])
6{
7 int i,n,r;
8
9 n = i = r = -1;
10 r = sscanf ("1234:567", "%d%n", &i, &n);
11 printf (format: "%d %d %d\n", r, n, i);
12 if (r != 1 || i != 1234 || n != 4)
13 abort ();
14 return 0;
15}
16

source code of glibc/stdio-common/scanf1.c