Thread: question about K&R example listing 1-6 Arrays

Hello everyone, here's the listing:

Code:

#include <stdio.h>

/* count digits, white space, others */

int main(void)
{
	int c, i, nwhite, nother;
	int ndigit[10];

	nwhite = nother = 0;
	for (i = 0; i < 10; ++i)
		ndigit[i] = 0;

	while ((c = getchar()) != EOF)
	{
		if (c >= '0' && c <= '9')
			++ndigit[c-'0'];
		else if (c == ' ' || c == '\n' || c == '\t')
			++nwhite;
		else
			++nother;
	}
	printf("digits =");
	for (i = 0; i < 10; ++i) /* recursively print every element in the array */
		printf(" %d", ndigit[i]);
	printf(", white space = %d, other = %d\n", nwhite, nother);

	return 0;
}

I have some problem understanding the

Code:

++ndigit[c-'0'];

line, I mean, does it browses sequentially in the ASCII table to seek for the value of c minus the value of the character '0' ?
If so, how can it find the value for the other digits 1-9?

Thank you in advance.

FSX