find if there is any repeated character in a given ascii string

dedup.c

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

/* c implementation to test is an ASCII string has deplicated characters */

/**
 * [main description]
 * @param  argc [number of argument]
 * @param  argv [argument values]
 * @return      [0 passed, 1 missed input, 2 failed]
 */
int main(int argc, char **argv)
{
	unsigned int hash[8]; 
	int i, j, k; 
	char *input; 

	if (argc < 2) {
		printf("Usage: %s string\n", argv[0]); 
		exit(1); 
	}
	input = argv[1]; 
	printf("Testing %s ...\n", input); 
	for (i=0; i<8; i++) { hash[i] = 0; } 
	for (i=0; i<strlen(input); i++) 
	{	

		j = input[i] / 32; k = input[i] % 32; 
		// this is how we check if the bit was set to 1
		if (hash[j] & (1<<k))
		{
			printf("There are more than one %c in the string.\n", input[i]); 
			exit(2); 
		}
		// This is how you set the kth bit to 1; 
		hash[j] |= 1 << k; 
		// BTW, to clear a bit, number &= ~(1 << x)
		// and to toggle a bit, number ^= 1 << x;
	}	 
	printf("No duplicating character found.\n"); 
	return(0); 
}