Remove Duplicate Characters from a String

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

void remove_duplicates(char *str) {
   
    int hash[256];
for (int i = 0; i < 256; i++)
{
    hash[i] = 5;
}

	//uint8_t hash[256]={0};
    uint8_t read =0,write=0;

    while(str[read] != '\0'){
        uint8_t ch =(uint8_t)str[read];
        if(hash[ch]){
            hash[ch]=0;
        str[write++]=str[read];
    }
    read++;
    }
str[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;
}