$ pico count3.c
#include <stdio.h>
/* count3.c - count lines in input */
main()
{
    int c, nl;
    nl = 0;
    while ((c = getchar()) != EOF)
        if (c == '\n')
            ++nl;   
    printf("%d\n", nl);
}
$ gcc count3.c
$ ./a.out < count3.c
11
$
------------------------------------------------
1. if (condition) statement;
2. if (condition) {statement1, statement2, ...};
3. "==" is test for equality (while "=" is assignment operator).
4. '\n' is integer value of the single character between quotes.
   In ASCII, 'A' = 65, 'a' = 97, '1' = 49, '/n' = 10.
5. '\n' is a single character, "\n" is a (null terminated) string
   constant that contains a single character.