Programming Language AINSI C Book

Question

There is an example from the book which is about a program that reads a set of text lines and prints the longest. I've understood almost all of the logic of the program but there is a piece of code bothering me. I can't understand "if (max > 0)
printf("%s", longest); "
Let's say the input is abcde then longest[0] will be a longest[1] will be b etc... But how can this program print the longest just by %s and longest. I know that arrays name act as a pointer. So longest will be longest[0] and thus only output should be 'a' according to my knowledge. I'd like to know when we write printf("%s", longest); does the program get all of the array one by one such as longest[0], longest [1] ... ? If not how does this part work?

#include <stdio.h>
#define MAXLINE 1000 /* maximum input line size */
int getline ( char line[], int maxline);
void copy ( char to[], char from[]);
/* print longest input line */
main()
{
int len; /* current line lenght */
int max; /* maximum lenght seen so far */
char line [MAXLINE]; /*current input line */
char longest [MAXLINE]; /* longest line saved here */
max = 0;
while ( (len = getline(line, MAXLINE)) > 0 ) {
if ( len > max) {
max = len;
copy(longest, line);
}
if (max > 0)
printf("%s", longest);
}
return 0;
}
/* getline: read a line into s, return lenght */
int getline(char s[], int lim) {
int c, i;
for ( i = 0; i < lim -1 && ( c = getchar()) != EOF && c != '\n' ; ++i )
s[i] = c;
if (c == '\n') {
s[i] = c;
++i;
}
s[i] = '\0';
return i;
}
/* copy : copy 'from' into 'to'; assume to is big enough */
void copy (char to [], char from[]) {
int i;
i = 0;
while ((to[i] = from[i]) != '\0')
++i;
}

Answer 1

If I understood you correctly you'd like to know how printf prints array of chars despite only knowing the address of the first element.
In C strings or rather arrays of chars have a null character '\0' at the end that determines the end of the string. So the string "abc" actually is { 'a', 'b', 'c', '\0' }. printf simply starts at the first char and prints every following char until '\0' is reached.

Answer 2

Yes I wanted to know that. Thank you very much. Now it makes sense. Have a nice day. I appreciate it :)