Remove Duplicate Characters from a String

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

void remove_duplicates(char *str) {
    char *run = str;
    int arr[256] = {0};
    char strr[101];
    int i = 0;
    while (*str)
    {
        if(arr[*str] == 0){
            strr[i++] = *str;
            arr[*str] = 1;
        }
        ++str;
    }
    strr[i] = '\0';
    i = 0;
    while (strr[i])
    {
        *run = strr[i++];
        ++run;
    }
    *run = '\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;
}