Remove Duplicate Characters from a String

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

void remove_duplicates(char *str) {
    char arr[256] = {0};
    char *read = str;
    char *write = str;
    while(*read != 0){
        char c = *read;
        if(arr[c] == 0){
            arr[c]++;
            *write = *read;
            read++;
            write++;
        }else{
            read++;
        }
    }
    *write = '\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;
}