Remove Duplicate Characters from a String

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

#define DUPLICATE_MARK '\x1b'

void remove_duplicates(char *str) {
    char *wr = str;
    char *rd = str;

    uint8_t unique_symbols[256] = {0};

    while (*rd != '\0') {
        if (!unique_symbols[(uint8_t)*rd]) {
            unique_symbols[(uint8_t)*rd] = 1;
            *wr = *rd;
            ++wr;
        }
        ++rd;
    }
    *wr = '\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;
}