Remove Duplicate Characters from a String

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

void remove_duplicates(char *str) {
    bool seen[265] = {false};
    int read_index = 0;
    int write_index = 0;
    char current_char;
    while((current_char = str[read_index]) != '\0'){
        if(!seen[(unsigned char) current_char]){
            seen[(unsigned char) current_char] = true;
            str[write_index] = current_char;
            write_index++;
        }
        read_index++;
    }
    str[write_index] = '\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;
}