Remove Duplicate Characters from a String

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

void remove_duplicates(char *str) {
	//Your logic here
    int seen[256] = {0};
    int i, w;
    w=0;
    for(i=0; str[i] != '\0'; i++)
    {
        unsigned char c = (unsigned char)str[i];
        if(!seen[c])
        {
            seen[c] = 1;
            str[w++] = (char)c;
        }
    }
    str[w] = '\0';

}

int main() {
    char str[101];
    fgets(str, sizeof(str), stdin);

    // Remove newline
    uint8_t i = 0;
    while (str[i]) {
        if (str[i] == '\n') {
            str[i] = '\0';
            break;
        }
        i++;
    }

    remove_duplicates(str);
    printf("%s", str);
    return 0;
}